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