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