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