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