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