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