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