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