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