、。
She gave me a haughty look and walked off.
Literal
She [topic-は] haughty expression [with-で] me [object-を] saw-and, walked-away.
高慢な ('haughty, arrogant, conceited') is a strong negative judgment — distinct from milder 偉そう ('acting big') or 自信満々 ('full of confidence'). The instrumental で on 表情 ('expression') marks 'with what kind of look': a manner-of-action use of で. 歩き去る is a compound verb fusing 歩く ('walk') + 去る ('leave, depart') = 'walk away, walk off.' Such ~去る compounds always denote leaving the scene: 立ち去る ('stand up and leave'), 飛び去る ('fly away').