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