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