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