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