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