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