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