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