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