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