She trained at one of the original Jedi temples and is now the protector of the sacred texts that she took from the library before it was destroyed. As the last Jedi (as far as we know, Filoni…), she’s also the protector of their entire culture in general (a thousand generations live in you now).
Also Rey might not even know about the colors, and lightsaber color lore is inconsistent and doesn’t matter anyway. Cal Kestis had a hot-pink one when I played Fallen Order.