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