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