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