The colors never switched: blue always represented the incumbent and red always represented the challenger.
What switched was the party in office -- Gore was blue in 2000 because the Democrat party was incumbent as Clinton was the outgoing president.
But I still remember Reagan's re-election map.
Dennis Miller was reminiscing about the 1984 election and said, "I mean, Walter Mondale made George McGovern look like William the Conqueror."