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