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