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