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