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