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