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