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