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