She has a look on her face as if she'd seen a ghost.
Literal
She [topic-は] ghost [even-でも] seen as-if face [object-を] is-doing.
幽霊でも見たかのような顔 — かのような ('as if') marks a hypothetical comparison. でも after 幽霊 adds 'even' or 'or something' — 'as if she'd seen a ghost or something.' 顔をしている means 'to have a [certain kind of] face/expression.'