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