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