I know this post is old, but just for info sake,
You can and should put a rinse on directly after shampooing relaxer out. The semipermanent rinse actually acts as a conditioner. You are actually lessening the intensity of the color by using a conditioner first or with the color. The only thing you should add is maybe some drops of protein. Think of the hair like a sponge. it can only soak up so much. So, filling the hair shaft with conditioner leaves little room for color. The color may take, but it will fade quicker, and for gray, it wont take as well. Just a little FYI. I think most directions tell you to put the color on directly after rinsing relaxer. and then after you shampoo the rinse out with a conditioning moisturizing shampoo, then comb some conditioner through and rinse to detangle.