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