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