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