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)(11,12)(13,14)(15,16)(19,23)(22,24)(25,26)(27,30)(28,31)(29,32)(33,36)(34,37)(35,38)(39,40)(1,3,6,4)(2,5,7,8)(9,10)(11,12)(13,14)(15,16)(18,21)(22,24)(26,27)(31,33)(32,34)(38,39)(2,7)(3,4)(10,14)(11,15)(17,18)(19,22)(20,21)(23,24)(25,27,30,26)(28,31,36,33)(29,32,37,34)(35,39,40,38)(1,4,6,3)(2,5,7,8)(9,11,13,15)(10,12,14,16)(25,28)(26,31)(27,33)(29,35)(30,36)(32,38)(34,39)(37,40)(1,5)(2,3)(4,7)(6,8)(9,12)(10,15)(11,14)(13,16)(17,19)(18,22)(20,23)(21,24)(25,29,30,37)(26,32,27,34)(28,35,36,40)(31,38,33,39)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.