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