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