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