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