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