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