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