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