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