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