I don't have many photos of bitones or bicolors to post for you - it's not something I looked for in the daylilies I have grown.
A Bicolor might have the front petals red, the back petals yellow.
A Bitone would have the front petals and back petals different shades of the same color... the front petals might be dark pink, and the back petals light pink.
Here is one I can think of... Dottie Warrell's "Douglas Debate"
I **think** this would be a bitone, because the back petals are similar in color to the front petals... just lighter. It is kind of on the border of biTONE and biCOLOR.