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