what evidence of racism in the workers can be seen?

Crooks is the only person of color on the ranch. He is the black stable hand and Candy's description, in chapter 2, tells us about the inherent racism against him.

"Sure. Ya see the stable buck's a nigger."

"Nigger, huh?" "Yeah. Nice fella too. Got a crooked back where a horse kicked him. The boss gives him hell when he's mad. But the stable buck don't give a damn about that. He reads a lot. Got books in his room."