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