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)(11,19)(12,21)(13,17)(14,16)(15,18)(20,23)(22,24)(26,30)(27,33)(28,34)(31,38)(32,37)(35,39) involution — undirected(2,5)(6,8)(9,11,15,14)(10,16,18,19)(12,22,13,20)(17,24,21,23)(25,26,28,30,29,32,34,37)(27,31,33,36,35,38,39,40)(1,3,4,7)(2,6,5,8)(9,12,15,13)(10,17,18,21)(11,20,14,22)(16,23,19,24)(25,27,34,39,29,35,28,33)(26,31,37,40,32,38,30,36)(9,13,15,12)(10,17,18,21)(11,20,14,22)(16,24,19,23)(26,32)(30,37)(31,38)(36,40)(9,14,15,11)(10,16,18,19)(12,22,13,20)(17,23,21,24)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.