Well there are no pictures, paintings, etc. of Sequoyah. There is only a painting of Thomas Haw which wore Sequoyah-like clothing and posed with Sequoyah's alphabet and turban for such a painting. There are no other paintings which refer to Sequoyah.
Histrorians as well as the Tsalagi (Cherokee people) do believe this is what Sequoyah were to look like and is a rather accurate depiction. I grew up learning that this was him and the Cherokee Nation (sovereign nation in US) applies this to be him.
The leaderhead would just need him in his blue dress attire, his Cherokee medallion, his red and white turban, and a more Caucasian look of Hiawatha for his face (Sequoyah is believed by many that he was half white while most Cherokees deny that). Cherokees anyways have fair skin than any other North American tribe has ever had.
I hope this helps.
Oh yeah and for a background, the inside of a tent/cabin/building or outside would work fine. For the Ancient era have him with no Turban and little clothes, Medieval a more primative turban and some or little clothes, and for Modern have him wearing a tux and either a turban or not.
Thanks.