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