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)(11,17)(12,23)(13,19)(14,24)(15,20)(16,21)(18,22)(25,26)(27,33)(28,32)(29,30)(31,35)(34,39)(36,37)(38,40)(1,3)(2,6)(4,7)(5,8)(9,11,16,14)(10,17,21,24)(12,15,22,19)(13,23,20,18)(26,30)(31,33)(32,37)(38,39)(1,3)(2,6)(4,7)(5,8)(9,12)(10,18)(11,15)(13,17)(14,19)(16,22)(20,24)(21,23)(25,26)(27,31)(28,32)(29,30)(33,35)(34,38)(36,37)(39,40) involution — undirected(1,3,5,8)(2,4,7,6)(9,13,16,20)(10,19,21,15)(11,18,14,23)(12,17,22,24)(25,27)(26,31)(28,34)(29,35)(30,33)(32,38)(36,40)(37,39)(1,4,5,6)(2,3,7,8)(9,14,16,11)(10,17,21,24)(12,19,22,15)(13,23,20,18)(1,3)(2,4)(5,8)(6,7)(9,15,16,19)(10,20,21,13)(11,22,14,12)(17,18,24,23)(25,28,29,36)(26,32,30,37)(27,34,35,40)(31,38,33,39)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.