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