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