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