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