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