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