Globally speaking, the color of the jacket is not that important. It is recommended however that you wear a color that is visually distinct and can easily be seen from afar. Something that draws attention to the human eye.
One-color that you should avoid at all costs is white. Imagine wearing white pants with a white jacket, and you are lost in the snow – no one will ever see you. That’s probably how military units camouflage themselves in the snowy mountains.