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