Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The entire body of the woman is Awrah in Salah (including her feet and her hair) except her face and hands according to the preponderent opinion of Muslim scholars. So, she should cover her whole body except what we have mentioned above. It should be noted here that the garments of the woman should be loose and thick enough to screen the colour of her skin. So, it is lawful for a Muslim woman to pray in any cloth that covers what we mentioned, that is loose enough and that does not reveal details of her body.
Allah knows best.