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