The color of the horse

The color of the horse can be any color other than Black and Brown.
If the color of the horse is Black - all are lying.
If the color of the horse is Brown - all are telling truth.
Thus, the horse is neither Black nor Brown.
If the color of the horse is Grey - Pinto and Sandy are telling truth whereas Andy is lying.
If the color of the horse is other than Black, Brown and Grey - Pinto is telling truth whereas Sandy and Andy are lying.
You must have noticed that for the given conditions, Pinto is always telling truth whereas Andy is always lying