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