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