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