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