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