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