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