Her Wikipedia article is here.
Marie Therese is dressed in an almost Lely-esque super-casual way, but in Grecian style with her over-dress organized with a waist cord and clasps in this Martignon portrait.
Keywords: Martignon, Marie Therese von Thurn und Taxis, Thurn und Taxis family, Esterhazy family, Princess, curly coiffure, head band, turban, chemise, cap sleeves, over-dress, strap sleeves, waist band, clasps, wrap