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