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