Why would the color fade anymore than any other color?
Here’s why:
The pigments used in the translucent stains that let you see through to the wood are organic. That is, they originate with plant and sometimes animal chemicals The drawback is that organic pigments are photosensitive - that is, a chemical reaction happens when they’re exposed to light.
The degree of photosensitivity among these pigments varies a great deal. For example, the pigments for blue stains are for whatever reason, especially photosensitive. This has everything to do with the particular chemicals and compounds that are used to create the pigment.
Those for other stains can be more or less sensitive, depending on what they’re made of. Red and brown stains are less photosensitive than blue. Yellow is kind of in-between. I think black stains aren’t too bad, but I don’t remember.
If, however, you don’t want your guitar to fade, the remedy is simple: keep it in a case when you’re not playing it. The longer you leave it out, the more it’s exposed to light, and the more fading you’ll see. Contrary to popular belief, any light source will trigger photosensitivity, though UV light is the most likely to cause fading; that has everything to do with the type of energy generated by the light source.
I keep my PRSes cased for other reasons, mostly because they’re easier to maintain, need fewer adjustments and string changes, and airborne things in houses like dust and oils floating around from activities like cooking affect the guitar less (the pots and switches stay cleaner and are less scratchy, etc.).
But keeping them cased has the nice side benefit of shielding them from light. So they fade less.