The four most popular college colors are red, gold, blue and black. Overall, red is the most popular color, commonly paired with white. Gold is the second most popular college color, often being paired with blue, red and black. The least common college colors are yellow and brown, although many teams choose to use the color yellow when playing on the field as opposed to their official gold.
There is likely a psychological component at play in the choices made by various universities for their official school colors. For example, studies have shown that people perceive red as angry, energetic and passionate - just what a sports team needs to succeed. It comes as no surprise, then, that red is so commonly chosen. To follow a similar line of thought, yellow is traditionally representative of cowardice, so it is no wonder that a college would not want yellow to represent them.
There have also been studies showing a correlation between the winning team and the color red. Again, this may be due to the subconscious understanding that those wearing red are dominant. However, there are additional theories suggesting that the color red attracts more fans to a team, thus boosting moral and leading them toward victory. There have also been studies that show that referees favor the color red, so it is likely that the teams in red are granted more leeway throughout a game.