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