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