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)(11,14)(12,17)(13,16)(15,20)(18,22)(19,24)(21,23)(25,26)(27,34)(28,36)(29,32)(30,33)(31,37)(35,39)(38,40) involution — undirected(2,6)(3,7)(10,11)(15,17)(16,18)(23,24)(25,27,30,32)(26,29,33,34)(28,35,37,40)(31,39,36,38)(1,3,5,7)(2,4,6,8)(10,11)(15,17)(16,18)(23,24)(28,37)(31,36)(35,40)(38,39)(1,4)(2,7)(3,6)(5,8)(9,11,14,10)(12,17,20,15)(13,16,22,18)(19,23,21,24)(25,28,30,37)(26,31,33,36)(27,35,32,40)(29,39,34,38)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,26)(27,29)(28,31)(30,33)(32,34)(35,39)(36,37)(38,40)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)(25,29)(26,32)(27,33)(28,38)(30,34)(31,35)(36,40)(37,39)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.