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