To give the highways A18 Messina-Catania or A19 Palermo-Catania: 
 

From the airports Catania Fontanarossa or Palermo Puntaraisi:
 

By train to the railway Station of Siracusa (or to the station of Noto with connecting train)

By ferry to the seaport of Catania or Palermo
 

From the most important Italian cities by bus, directly to Noto