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