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