Margy was born in Alice Springs in 1978. Her father Kelly Williams, is from Pukatja (Ernabella), South Australia and her mother Aleen Cooper, is from Irrunytju (Wingellina), Western Australia. Margy grew up with her grandmother, Kuntjil Cooper Napurulla, in Irrunytju country. Her grandmother was both in 1920 at Irrunytju rockhole and was a senior Pitjantjatjara artist with extensive knowledge of Irrunytju country. Margy remembers watching her grandmother paint from a young age, helping her with cups of water and listening to her stories. It is from her grandmother that Margy was passed down the Tjukurrpa (dreaming) of Minyma Kutjara (Two Sisters). Since the passing of her grandmother, Margy has continued to paint this Tjukurrpa. In 2017 she came to Ikuntji (Haasts Bluff) where she now lives with her partner, Joseph Zimran.