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