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