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