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