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