i was going to say , feathers? but instead of choosing blue or grey, you could make it a grey base with blue strips or patterns. think abe sapian from hellboy. or predator. look up up colorful lizards for reference. that is what the Hollywood painters do.. we really do not know what color dinosaurs were. when i was kid, they were all green or grey now the latest research suggest they may be a multiple colors.
hope this helps.