Eric,
Female panthers are capable of many color changes, which while not as colorful and pretty (IMO) as that of males, are more dramatic with regard to changes in pattern, and extreme in color variance. I am assuming that the top picture in the first post is the most recent. Providing she is still alert and eating, ther is no color there to worry about. When a female panther is ready to breed, she will show the more uniform dull orange/pastel seen there, and be far more distincively marked, as in the other pictures, when she is not. That doesn't mean she's ready to breed, only that you may want to bring a male close to her and see if she remains that lighter color, and acts unimpressed. Such "non-reaction" by a healthy female in close proximity to a male is a pretty good sign she's ready to breed. Any negative reaction ... gaping, darkening of color, swaying, lateral expansion, rapid retreat, means "not this time"! Good luck.
Jim Flaherty
The Chameleon Company, LLC