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