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