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