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