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