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