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