One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,7)(6,8)(9,10)(11,19)(12,16)(13,25)(14,18)(15,22)(17,28)(20,36)(21,34)(23,35)(24,33)(26,30)(27,32)(29,39)(31,38)(37,40) involution — undirected(1,2,4,6)(3,8,7,5)(9,11,14,21)(10,15,18,30)(12,20,24,37)(13,26,28,22)(16,31,33,29)(17,34,25,19)(23,39,27,38)(32,40,35,36)(1,2)(3,8)(4,6)(5,7)(9,12,14,24)(10,16,18,33)(11,20,21,37)(13,27,28,23)(15,29,30,31)(17,35,25,32)(19,36,34,40)(22,39,26,38)(11,21)(15,30)(19,34)(20,37)(22,26)(29,31)(36,40)(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.