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