It's good that bed liners are now available in colors other than your basic black. The Herculiner colors you can get are gray, white and red as well as black.
As you look at all the options for liner paint including the Herculiner bed liner you can see quite different approaches to colors in liners. Some of the liner coatings are made to be UV resistant and that will be pointed out clearly. In many cases what you get for bed liner coatings is subject to fade with exposure to the sun.
If you want more colors than just black, red, gray and white you will want to look elsewhere than Herculiner.
For example the Al's Bed Liner comes in just black, tan and gray as standard color. Note that it comes with pigments, but the base can be tinted to virtually any color you like. But as an option one can also duplicate pretty much any texture or hardness as well. By mixing in automotive pigments and metal flake the paint can duplicate most any color. It's a totally variable colored bed liner paint. The liner people can direct you on how to get that done.
But the liner paint color options could be used to make multiple colors in the same bed too. Or one could make designs on the bed for that matter.
But the standard Herculiner colors of black, white, gray and red open up a lot of possibilities for you to make a bed look unique and interesting.