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