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)(11,15)(12,13)(14,16)(17,21)(18,19)(20,22)(23,24)(29,37)(34,38)(35,40)(36,39) involution — undirected(2,5)(6,7)(9,11,14,20)(10,15,16,22)(12,18,17,23)(13,19,21,24)(25,26)(27,32)(28,33)(29,34)(30,31)(35,39)(36,40)(37,38)(1,2)(3,6)(4,5)(7,8)(10,16)(12,17)(15,22)(18,23)(26,31)(28,32)(34,38)(36,39) involution — undirected(1,3)(2,6)(4,8)(5,7)(9,11)(10,15)(12,18)(13,19)(14,20)(16,22)(17,23)(21,24)(25,27,30,33)(26,32,31,28)(29,35,37,40)(34,39,38,36)(9,12,14,17)(10,13,16,21)(11,18,20,23)(15,19,22,24)(25,28,30,32)(26,33,31,27)(29,36,37,39)(34,40,38,35)(9,13)(10,17)(11,19)(12,16)(14,21)(15,23)(18,22)(20,24)(25,29)(26,34)(27,35)(28,36)(30,37)(31,38)(32,39)(33,40) 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.