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