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