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