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