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