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