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