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