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