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