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