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