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