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