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