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