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