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