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