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