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