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