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