I mean, yeah, that's what Wikipedia says, but I briefly browsed around maps like the OP for France's colonial empire in Africa and I've seen greens and yellows, but no blues. That's both English maps and French maps.France was historically strongly associated with blue since the 1300's and white since the mid 1600's. Blue came back in force in the late 18th century
Actually as I typed this I did find a German map with the French being blue, but I don't think it's quite nearly as universal a color association as sites like Wikipedia make it out to be. Limited sample size, though, so take what I'm saying with a grain of salt!