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