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