If you're playing as a dino you have to force tame to ride, you have to use console commands to color it. Once you enable cheats, you go to the dinosaurs page on the wiki to see what regions you can color and then look up the color codes.

This is the code you're going to be using in the console:
SetTargetDinoColor <ColorRegion> <ColorID>

So for example you want the main body of a trike to be CYAN. To turn the main part of it CYAN you'd open the console and type this:

SetTargetDinoColor 0 5

You have to do it for each region of the dino. Also, make sure you're looking right at the dino and standing next to it while using the command, otherwise it won't work.

Hope this helps~