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