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