I read before that her hair was dark blond but she used to dye it chestnut for making the flowers with the ones she loved to decorate her hair to stand out. It's likely that she continued dying her hair when she became even older, I'm not sure if she allowed to have gray hair, knowing her I doubt so.
About her eyes in many paintings they look light brown and in others even blue, I'm sure that they had a dark color, possibly light brown or even olive, as the majority of her siblings, except, of course, of Karl Theodor and Sophie who had light blond hair and blue eyes.