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