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