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