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