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