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