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