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