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