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)(11,18)(12,14)(13,15)(16,19)(17,21)(20,24)(22,23)(10,14)(12,21)(15,17)(16,18)(19,22)(23,24)(25,26)(27,34)(28,32)(29,37)(30,33)(31,35)(36,39)(38,40) involution — undirected(1,3,4,8)(2,5,6,7)(10,15)(14,17)(16,23)(18,24)(25,27,30,36)(26,31,33,40)(28,35,29,38)(32,39,37,34)(9,11,13,20)(10,16,15,23)(12,22,21,19)(14,18,17,24)(25,28,30,29)(26,32,33,37)(27,35,36,38)(31,39,40,34)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.