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)(25,26,30,34)(27,28,32,31)(29,37,38,33)(35,39,40,36)(1,3,5,8)(2,6,7,4)(9,11,14,19)(10,15,17,12)(13,18,22,23)(16,21,24,20)(1,3)(2,4)(5,8)(6,7)(25,27)(26,31)(28,34)(29,35)(30,32)(33,39)(36,37)(38,40) 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)(26,28)(29,35)(30,32)(31,34)(33,36)(37,39)(38,40) involution — undirected(9,11)(10,15)(12,17)(13,18)(14,19)(16,21)(20,24)(22,23)(25,28)(26,32)(27,34)(29,36)(30,31)(33,40)(35,37)(38,39) involution — undirected(9,13)(10,16)(11,18)(12,20)(14,22)(15,21)(17,24)(19,23)(25,29,30,38)(26,33,34,37)(27,35,32,40)(28,36,31,39)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.