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