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