One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(9,10)(11,14)(12,23)(13,18)(15,31)(16,21)(17,27)(19,24)(20,33)(22,29)(25,37)(26,36)(28,40)(30,34)(32,39)(35,38) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,11,14,10)(12,20,26,17)(13,18,16,21)(15,22,30,19)(23,27,36,33)(24,34,29,31)(25,32,28,35)(37,38,40,39)(9,12,24,38,16,28,30,33,14,26,29,39,13,25,15,27)(10,17,31,37,18,32,22,36,11,20,34,40,21,35,19,23)(3,8)(5,7)(9,13,14,16)(10,18,11,21)(12,25,26,28)(15,29,30,24)(17,32,20,35)(19,31,22,34)(23,37,36,40)(27,39,33,38)(2,6)(5,7)(10,11)(12,26)(18,21)(19,22)(25,28)(27,33)(31,34)(38,39) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.