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