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