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