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