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