I mean, with that POD this isn't even a challenge, because that's the exact timeframe the scheme got locked in. Historically, outlets were not consistent with each other or even themselves, alternating colours between elections (or assigning colour based on incumbent/challenger rather than party affiliation). It only coalesced when the networks all decided to go with Red Republican/Blue Democrat for consistency and— more importantly— the 2000 election was so close, and subject to recounts and litigation, that the electoral maps were constantly in the news as a visual guide.
So with a POD in 2000, flipping the party colours is as simple as having the networks decide on the opposite scheme, or for the 2000 election to be a clear victory (for either party) so that the next election alternates colours again and the cycle continues…