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