I use Clojure professionally, but it's readable to me. I would personally encode the color merging rules differently since it looks too obscured as-is. But I think what doesnt help is the lack of types (or schemas) and the unhelpful function names, as described by another commenter.

Also,

  (apply merge-with {} ...)

is pretty "evil" in the sense that it's a very roundabout data transformation and would likely not pass code review at my company.