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