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