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