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