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