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)(11,22)(12,18)(13,19)(14,31)(15,20)(16,21)(17,25)(23,39)(24,37)(26,35)(27,33)(28,40)(29,38)(30,34)(32,36) involution — undirected(9,11,14,25,16,26,15,32)(10,17,20,22,21,36,31,35)(12,27,28,24,13,30,29,23)(18,37,38,33,19,39,40,34)(2,5)(6,8)(9,12,15,29,16,13,14,28)(10,18,20,38,21,19,31,40)(11,23,25,27,26,24,32,30)(17,33,35,37,36,34,22,39)(9,13,15,28,16,12,14,29)(10,19,20,40,21,18,31,38)(11,24,25,30,26,23,32,27)(17,34,35,39,36,33,22,37)(1,3,4,7)(2,6,5,8)(12,13)(18,19)(23,24)(27,30)(28,29)(33,34)(37,39)(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.