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