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