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