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