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