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