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