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)(11,16)(12,15)(13,17)(14,19)(18,23)(20,21)(22,24)(25,26)(27,34)(28,30)(29,32)(31,33)(35,36)(37,39)(38,40) involution — undirected(1,2,4,6)(3,5,8,7)(9,11)(10,14)(12,18)(13,19)(15,22)(16,17)(20,24)(21,23)(25,27,31,29)(26,32,33,34)(28,37,38,35)(30,36,40,39)(1,2)(3,5)(4,6)(7,8)(12,20)(15,21)(18,24)(22,23)(26,33)(28,38)(32,34)(35,37) involution — undirected(1,3,4,8)(2,5,6,7)(9,12,13,20)(10,15,17,21)(11,18,19,24)(14,22,16,23)(25,28,31,38)(26,30,33,40)(27,35,29,37)(32,39,34,36)(9,11)(10,16)(12,18)(13,19)(14,17)(15,23)(20,24)(21,22)(25,29,31,27)(26,34,33,32)(28,37,38,35)(30,36,40,39)(9,10)(11,14)(12,21)(13,17)(15,20)(16,19)(18,23)(22,24)(25,30)(26,28)(27,36)(29,39)(31,40)(32,37)(33,38)(34,35) involution — undirectedA 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.