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