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