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