Current Canada has a population of 35 million, roughly half the size of any developed and democratic country that could today be feasibly be considered a major military power in a conventional sense (ie. the UK and France), and roughly one tenth the size of the population of the current super power (the US). The disparity in population sizes is even greater in the WW2 era: In 1945 Canada's population was only 12 million people to the UK's nearly 50 million and France's 40 million and the US's roughly 140 million. Canada simply doesn't have the population to sustain a large world class military during peacetime, although its large (relative to its population size) industrial base allowed it to quickly build and equip powerful army and navy and air force very quickly in ww2 (especially the navy which was virtually non-existent in 1939 to 300+ ships at the end of ww2 to protect a very large merchant marine. Also it should be noted that Canada essentially maxed out its financial capabilities in WW2 to field the force it did and supply the UK, and at one point faced an economic collapse in the countries ability to fund the allied war effort which was only alleviated by FDR's Hyde Park declaration which essentially committed the US to buy pretty much any war materiel Canada produced and then to sell it to the UK for credit as part of the lend-lease program. This is why Canada was able to produce staggering amounts of certain types of military equipment for the allies such as 500 000 CMP military trucks in WW2 (more than Germany), and allowed for Canada to run its own version of Lend-Lease, the Billion Dollar Gift and Mutual Aid. These kinds of disproportionate exertions would simply have been impossible in peace time, even if the Canadian public had been willing to fund a military to an extent proportionate the the Americans post-ww2.
The one way you can have a post-ww2 Canadian military that is a significant force to be reckoned with is if Canada pursues nuclear weapons (likely in conjunction with the UK effort). A country with a nuclear warhead stockpile and the delivery systems to inflict those weapons on distant countries automatically has to be considered a major military power. With the largest Uranium reserves on Earth, an early head start on nuclear technologies and infrastructure (involvement of Canadian scientists and industry in prewar nuclear research and later Manhattan project, creation of the first nuclear reactor outside of the US), Canada certainly has the potential to become a nuclear power, if not with an entirely independent program (a la France) then certainly as a full partner in a project with the UK, contributing strong research facilities and a huge amount of fissionable material to the joint project. Indeed the US eventually tried to pressure Canada to arm itself with American manufactured nuclear weapons, so even if a joint project Canadian project falls through there is a chance for a nuclear armed Canada operating US warheads, similar to the deal with the UK. The big reason none of this happened was a complete lack of public interest in a Canadian nuclear weapons program or even hosting foreign made nuclear weapons. However the Canadian civilian nuclear sector is definitely a major player on the international energy market with CANDU reactors and CANDU derivatives being the most successfully exported reactor in the world outside of American produced models (present in India, Pakistan, South Korea, China, Romania and Argentina with China), as well a well established nuclear research sector (often based around the SLOWPOKE mini reactors at Canadian Universities) as well as producing the bulk of the world supply of medical isotopes at the Chalk River Reactor, all of which definitely shows the infrastructure and technology necessary to create a nuclear program was and still is present in Canada, it is just there is no desire to do so and there would need to be a major POD to do so. To be blunt it is just so much cheaper for Canadians to outsource nuclear deference to the US as the two countries are geo-strategically joined at the hip due to the massive shared border. So instead Canada is happy to make a tidy profit selling uranium to the US so they can build weapons to defend both countries and to selling nuclear reactors to the rest of the world (which occasionally bit Canada in the ass as in the case where Canadian reactors were used to produce the fissionable material for India's first atomic bomb).
As a whole why would Canada even want a major military? Canada doesn't share any borders with an unstable or hostile neighbor (no jokes about the US please), unlike European nations in the Cold War Canada never faced any realistic scenario involving a foreign invasion and even going beyond that, Canada has been under the direct military protection of two successive Superpowers since the country's inception in 1867. Indeed, as soon as the UK began to weaken the US moved to directly protect Canada (Roosevelt's 1939 Queen's University Address directly stated that any foreign power attempting to invade Canada would face a declaration of war from the US and this was reinforced following the Ogdensburg agreement and the creation of the Permanent Joint Board of Defense in WW2). To be blunt, Canada faces practically no chance of a situation occurring where it would be under a conventional military attack from another state and even if it did, it could quickly lean on its powerful allies chiefly the United States to defend it as such the need for a large standing military force is very small, and that maintaining a WW2 level of military power is simply a waste of resources. What Canada needs in terms of military force is rather, a small mobile force capable of supporting its commitment to allied operation overseas as well as a strong anti-terrorism force to protect from unconventional attacks (basically the same model it has now). In short Canada's privileged geo-strategic position in the world renders a large military redundant and you would need a big POD to change this fact.