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