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