It is very unusual for coyotes to attack humans. I'm wondering whether it might have been timber wolves that actually attacked her?
Around here, coyotes have "attacked" walkers ---- who were walking male dogs. In all cases, it was male coyotes picking up the related canine pheremones from the dogs, and reacting to that. The dogs were considered to be territorial competitors to the coyotes, hence the attack. The human walkers just happened to be in the way and got bitten.
In other cases I've read of elsewhere, there were occasional "attacks" on humans when they were walking female dogs (yeah, bitches) that were in heat. Being that coyotes and dogs are the same genus and thus are cross-fertile, the male coyotes moved in to mate. I'm guessing a few of those "attacks" on humans were actually dry-humped legs.