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