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)(27,33)(28,36)(30,38)(32,39)(34,40)(35,37)(2,5)(3,7)(9,11)(10,16)(12,18)(13,19)(14,22)(15,20)(17,23)(21,24)(25,26)(27,34)(28,32)(29,31)(30,35)(33,40)(36,39)(37,38) 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)(25,27)(26,30)(28,37)(29,35)(31,34)(32,40)(33,36)(38,39)(2,5)(6,8)(9,13,15,14)(10,17,12,21)(11,19,20,22)(16,23,18,24)(26,31)(27,35)(32,39)(33,37)(9,14,15,13)(10,17,12,21)(11,19,20,22)(16,24,18,23)(26,31)(30,34)(32,39)(38,40)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.