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