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