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