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