Do you mean the process of making color and how it is applied to the belts or the reason the belts are the color they are??
Oh **** I didn't realize anyone ever responded. I was just curious about the reason myself. I know of the LPRR era sashes and colors and what those were for, and I assume it's something to do with the bodies colors, but I can't find a connection or even a reason for WBC to be green and IBF red etc. They look nice, having those colors. I really like the EBU blue though. I assume it's blue because EU is blue but don't know my ass really.