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