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