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