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