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