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