[Chimera-users] How do I colour all my hydrogen atoms grey?

Hello, I imported an x,y,z model of water molecules into Chimera. I want to create an image of my water structure so I am setting the background to grey. That works. But I would prefer to set the hydrogen atom colour to light grey. I can't work out how to do that. I can select each individual atom, and then colour edit it but that will take ages. Is there a simple command line solution? Thanks Mazin