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