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)(11,16)(12,25)(13,23)(14,18)(15,20)(17,29)(19,27)(21,28)(22,32)(24,34)(26,33)(30,36)(31,35)(37,39)(38,40) involution — undirected(2,5)(6,8)(9,11)(10,16)(12,26)(13,19)(14,22)(15,24)(17,28)(18,32)(20,34)(21,29)(23,27)(25,33)(30,38)(31,37)(35,39)(36,40) involution — undirected(1,3,4,7)(2,6,5,8)(9,12,27,39,15,30,14,29)(10,17,18,36,20,37,19,25)(11,21,22,38,24,35,23,26)(13,31,34,40,32,28,16,33)(9,13,14,16,15,32,27,34)(10,11,19,23,20,24,18,22)(12,28,29,40,30,31,39,33)(17,35,25,38,37,21,36,26)(2,5)(6,8)(9,14,15,27)(10,18,20,19)(11,22,24,23)(12,29,30,39)(13,16,32,34)(17,36,37,25)(21,38,35,26)(28,40,31,33)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.