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