I worked in a hangar and the floor was painted white. Reflected the light nicely. My buddy worked in the Canadian Airline hangar and all the concrete was made with white quartz sand so it reflected light. Later I worked in a machining plant where all the floors were unpainted concrete. Dark, dirty and dingy. They built an addition that had the ceiling, concrete walls and floors painted white. Bright and clean. Nice side to work in. If you want colour paint the machines, window trim and doors. Leave the floors light grey or white. Right now I have unpainted OSB on the walls, ceiling and floor. If it weren't for the bright lights and lots of windows I would hate it. That's how I see it but you do what you want. It's only paint so you can always do it agian.
Pete