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