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