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