Though it's really hard to tell, my initial reaction was silver bay roan sabiono. Many on here have posted sooty chestnut, and it's often difficult to tell the difference from a silver bay and a sooty chestnut (especially if the colouring isn't strong), but here are my reasons for my guess. A silver bay is still a bay, meaning that it will still have it's black or dark points on its legs, mane, and tail. However the silver mutes it, and when accompanied with roan, appears a dull, dirty grey. In the case of your horse, she still has a mixture of black hairs in her mane, and her legs (especially the back of the hinds) looks significantly darker than other points of her coat. Also, when clipped a bay will often come out looking almost greyish (kind of like a grullo) where as a chestnut will come out peachy coloured. Because in the picture where you say she is clipped her body looks darker (and more grey) rather than lighter (and more peach), that's making me think she has a bay base.
All that being said, the two colours are still very similar, and a genetic test is the only thing that will tell you with certainty what she is.