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