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