This should be the setup once Human is installed, it bakes them with display color. You should make a layer in Rhino and use that layers name in the Human component, in the case of my screenshot it is the layer called gradient. Make the boolean toggle true to bake, then false to turn it off.
bake random colors.gh (10.2 KB)
Also so you know, changing the Seed input of random will change the randomization of the color.