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