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