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