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