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