Bevel Mask

Customize Bevel And Sides shaders.

Floor Generator has Bevel and Extrude H parameters which allow you to get the desired shape of each board. Using "Bevel" or/and "Sides" Attribute Nodes you can change shader/color of flooring bevel or/and sides of each plank.

It may also be a nice idea to create your own mask for each board to get an interesting result. Apply it using MultiTexture Node.