This is a caricature showing d’Eon de Beaumont is half male and half female attire. This was a common joke at the time, and there are actually records of bets made as to which sex d’Eon actually was.
The full caption reads: Mademoiselle de Beaumont or The Chevalier D’Eon Female minister plenipo. Capt. of Dragoons &c. &c.
From the London Magazine, xlvi. 443. Published Oct 1, 1777.
Retrieved from The Library of Congress.