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