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