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