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