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)(11,17)(12,15)(13,16)(14,19)(18,21)(20,23)(22,24)(25,26,29,32)(27,30,34,38)(28,31,35,39)(33,37,36,40)(2,5)(6,7)(9,11)(10,14)(12,18)(13,19)(15,22)(16,17)(20,24)(21,23)(27,33)(28,35)(30,37)(31,39)(34,36)(38,40) involution — undirected(9,12)(10,15)(11,18)(13,20)(14,21)(16,23)(17,22)(19,24)(25,27,29,34)(26,30,32,38)(28,36,35,33)(31,40,39,37)(1,3,4,8)(2,6,5,7)(10,16)(12,20)(14,17)(18,24)(27,34)(30,38)(33,36)(37,40)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.