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