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