Stats in that HUD are colored based on other stats for the players in question. If you mouseover the individual stats it should tell you what the color value is. For example, VP$IP is colored by limp/fold to raise. In this case, when the player has 0-10% Limp/Fold, his VP$IP is red. 10-20% is light red, and continuing in 10% blocks next is orange, then yellow, dark green, green, light green, blue, cyan, and magenta. The order is always held constant so yellow is always higher than orange, etc. For 3-bet numbers the numerical range is compressed to a 2% range (so red is 0-2, light red 2-4, etc), given that 3-bet numbers are so much smaller.