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