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