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