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