If you have not enabled cheats do so if needed by using: "EnableCheats AdminPasswordHere"
In the Tab command type in: "admincheat settargetdinocolor ColorRegionNumber ColorID" To explain the code a bit,the region number is the area to paint on the dino (to see the regions 1-6 visit the specific dino page by clicking on the entity names HERE) and the color ID numbers are listed 1-56 HERE.
Press enter while still aiming at the dino and that is it. Pretty simple.
You will need the Color IDs and Region Numbers. The regions are set different on each dino so you will want to see the Color Regions and the effected areas that are being recolored. Visit the links given to find the Wikis for the Color IDs and Regions.
Note: Some modded dinos have custom regions and may have mixed up Color IDs or some may not even allow color changes.