。
At the sight of all that blood, she recoiled in horror and looked away.
Literal
She [topic-は] large-quantity [genitive-の] blood [object-を] eye-do-and horror [with-で] face [object-を] turned-away.
Two idioms working together. 目にする ('to see, witness, lay eyes on') is more vivid than the bare 見る — the literal 'put it to one's eye' frames it as an unintentional or impactful sighting. 顔をそむける ('to turn one's face away') is the standard collocation for averting one's gaze, with そむける ('avert, turn against') taking 顔 or 目 as object. The で in 恐怖で is the causal/source-of-emotion で ('out of, from'), distinct from instrumental で ('with').