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)(12,16,21,20)(19,23,24,22)(25,26,31,36)(27,29,34,32)(28,33,30,35)(37,40,38,39)(1,2)(3,5)(4,6)(7,8)(9,10)(11,15)(12,20)(13,14)(16,21)(17,18)(19,23)(22,24)(25,27,31,34)(26,32,36,29)(28,38,30,37)(33,40,35,39)(10,14)(11,18)(16,20)(19,24)(25,28,31,30)(26,33,36,35)(27,37,34,38)(29,40,32,39)(9,11,13,18)(10,15,14,17)(12,19,21,24)(16,22,20,23)(25,26)(27,32)(28,33)(29,34)(30,35)(31,36)(37,39)(38,40)(1,3,4,7)(2,5,6,8)(9,10)(11,15)(12,20)(13,14)(16,21)(17,18)(19,23)(22,24)(25,29,31,32)(26,34,36,27)(28,39,30,40)(33,37,35,38)(9,12,13,21)(10,16,14,20)(11,19,18,24)(15,22,17,23)(25,30,31,28)(26,35,36,33)(27,38,34,37)(29,39,32,40)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.