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)(26,31)(27,34)(28,29)(32,39)(33,37)(38,40)(9,11)(10,14)(12,18)(13,17)(15,21)(16,22)(19,24)(20,23)(25,26)(27,32)(28,31)(29,37)(30,33)(34,40)(35,39)(36,38) involution — undirected(1,3,4,8)(2,5,6,7)(10,15)(11,17)(16,19)(18,23)(25,27,30,34)(26,32,33,40)(28,36,29,35)(31,38,37,39)(11,17)(14,21)(18,23)(22,24)(25,28,30,29)(26,31,33,37)(27,35,34,36)(32,39,40,38)(9,12,13,20)(10,16,15,19)(11,18,17,23)(14,22,21,24)(27,34)(32,40)(35,36)(38,39)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.