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