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