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