Doesn't need to be colors (for people with color blindness for example) could be patterns. Point is you make the colors/patterns boring to interesting and exciting. Don't think a drawing/pattern is exciting? Think of any shiny-attraction gimmick games have for imaginary points. Could be the delicious candies of candy crush (ugh) or the dazzling gems of bejeweled or the sweet sound of the tetris longbar that gets you 4 row clears with sweet sounds. It's a psychological thing that garners positive reinforcement in a way.

Really, I want people to feel good playing the game.
Failing a boss and not knowing if it's you isn't a good feel.
Failing a boss and knowing it's not you feels better, and limits the finger pointing drama as everyone is focus on their own thing.
Failing a boss and knowing it is you is arguably better since you can focus more and tighten your rotation better. You could also practice on a dummy/mobs to get the Super-level of the "meter".

It's just a gimmick, but it's a needed gimmick if there's content locked behind/gated behind DPS checks.

...really want some feedback though.