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