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)(11,19)(12,13)(14,17)(15,18)(16,22)(20,23)(21,24)(25,26,32,38,31,37,30,36)(27,34,28,35,39,33,29,40)(1,3)(2,5)(4,8)(6,7)(9,11)(10,16)(12,20)(13,21)(14,23)(15,22)(17,24)(18,19)(25,27)(26,33)(28,32)(29,30)(31,39)(34,37)(35,36)(38,40) involution — undirected(3,8)(5,7)(9,12,15,17)(10,13,18,14)(11,20,22,24)(16,21,19,23)(25,28)(26,34)(27,32)(29,31)(30,39)(33,37)(35,36)(38,40)(2,6)(5,7)(9,13,15,14)(10,17,18,12)(11,21,22,23)(16,24,19,20)(25,29,31,28)(26,35,37,40)(27,30,39,32)(33,36,34,38)(9,14,15,13)(10,17,18,12)(11,21,22,23)(16,20,19,24)(25,30,31,32)(26,36,37,38)(27,28,39,29)(33,40,34,35)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.