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