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