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