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