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