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