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