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)(11,18)(12,17)(13,16)(14,19)(15,22)(20,23)(21,24)(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)(10,15)(12,20)(13,21)(14,22)(16,23)(17,24)(18,19)(26,31)(27,33)(34,39)(35,40) involution — undirected(1,3,5,4)(2,6,8,7)(9,12,14,13)(10,16,19,17)(11,20,22,21)(15,23,18,24)(25,27,30,33)(26,32,31,28)(29,35,38,40)(34,37,39,36)(9,13,14,12)(10,17,19,16)(11,21,22,20)(15,24,18,23)(1,3,5,4)(2,6,8,7)(9,11)(10,18)(12,20)(13,21)(14,22)(15,19)(16,24)(17,23)(25,28,30,32)(26,33,31,27)(29,37,38,36)(34,35,39,40)(1,4,5,3)(2,7,8,6)(9,10)(11,15)(12,16)(13,17)(14,19)(18,22)(20,23)(21,24)(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.