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