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