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