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