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