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