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