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