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