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