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