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