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