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