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