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