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