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