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