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