You can see that Vance was still kind of hanging on to her classic depiction, in which her hair mass is actually a bunch of snakes.
Milt Kahl who animated the villainess didn't go quite as far and drew her hair more conventionally.
This of course makes complete sense since we are not dealing with Greek mythology here but instead with New York during the 1970s.
But Milt kept Vance's overall idea for the character's staging.
He mentioned in an interview that Medusa treats the phone's hand set as if it were Snoops. She is mad at him for not being able to control Penny. So she shakes the hand set, pokes it with her finger etc.
That thing represents Snoops to her. A fun way to approach this scene from an acting and animation point of view.
A few terrific thumbnail sketches for this section of the film.
A felt pen sketch that shows Medusa's unusual and entertaining body proportions.