COLOURlovers is a creative community where people from around the world create and share colors, palettes and patterns, discuss the latest trends and explore colorful articles... All in the spirit of love
This explains several ways to use consistent colors across plots (same way works with scales). However, the easy way explained in one of the alternative answers does not seem to work for some versions of R/ggplot2. Opting for the accepted answer always works though.
COLOURlovers™ is a resource that monitors and influences color trends. COLOURlovers gives the people who use color - whether for ad campaigns, product design, or in architectural specification - a place to check out a world of color, compare color palet