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