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)(14,16)(15,19)(17,22)(18,23)(20,24)(25,26)(27,31)(28,36)(29,30)(32,37)(33,35)(34,39)(38,40) involution — undirected(1,2,4,5)(3,6,7,8)(9,11)(10,15)(12,16)(13,18)(14,19)(17,23)(20,21)(22,24)(26,30)(31,33)(32,36)(38,39)(10,16)(12,15)(17,21)(20,23)(25,26)(27,33)(28,32)(29,30)(31,35)(34,39)(36,37)(38,40) involution — undirected(9,11)(10,15)(12,16)(13,18)(14,19)(17,23)(20,21)(22,24) involution — undirected(9,12,14,15)(10,11,16,19)(13,20,22,23)(17,18,21,24)(25,27)(26,31)(28,34)(29,35)(30,33)(32,38)(36,39)(37,40)(1,3,4,7)(2,6,5,8)(9,13,14,22)(10,17,16,21)(11,18,19,24)(12,20,15,23)(25,28,29,37)(26,32,30,36)(27,34,35,40)(31,38,33,39)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.