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)(11,19)(12,15)(13,23)(14,18)(16,21)(17,20)(22,24)(25,26)(27,30)(28,32)(29,31)(33,37)(34,39)(35,38)(36,40)(9,11,20,22,14,21,13,12)(10,15,23,16,18,24,17,19)(25,27,28,34,29,35,36,33)(26,30,32,39,31,38,40,37)(1,3,4,8)(2,5,6,7)(11,21)(12,22)(15,24)(16,19)(27,33)(28,36)(30,37)(32,40)(34,35)(38,39)(9,12,13,21,14,22,20,11)(10,16,17,15,18,19,23,24)(26,31)(30,38)(32,40)(37,39)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.