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