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