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