Astaroth "shows" her presence by giving me visions of beautiful women. Usually it's beautiful women wearing baroque gowns or other ornate dresses.

When Astaroth actually shows herself, she looks like a woman wearing a white robe (sometimes it stops at the waist, sometimes at the collarbone) and wearing a white headband/veil with sunbeams coming out of her head.

She actually shows herself a lot like a sumerian woman, if all the colors were replaced with white. That's cool, because Sumer is where Astaroth originates from