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