Sayyidah Aishah (may Allah be pleased with her) says that a woman in ihram may wear whatever clothes she wishes, except a garment touched by wars or saffron, and she should wear neither a burqa nor a face veil, and if she wishes she may let a cloth hang down over her face.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9050