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