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