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)(13,22)(14,17)(15,20)(19,24)(21,23)(25,26)(27,34)(28,36)(29,33)(30,31)(32,35)(37,40)(38,39) involution — undirected(1,2)(3,8)(4,5)(6,7)(9,11)(10,15)(12,21)(13,19)(14,20)(16,24)(17,18)(22,23)(25,27,29,30)(26,31,33,34)(28,35,37,38)(32,36,39,40)(2,5)(6,8)(25,28,29,37)(26,32,33,39)(27,35,30,38)(31,36,34,40)(1,3,4,7)(2,6,5,8)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(26,33)(31,34)(32,39)(36,40)(2,5)(6,8)(9,13,14,12)(10,16,17,22)(11,19,20,21)(15,24,18,23)(25,27,29,30)(26,31,33,34)(28,35,37,38)(32,36,39,40)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.