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