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