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