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