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