Answer is: the polarity arrows should go from sulfur (S) to the oxygen (O).
The magnitude of the dipole depends on the difference in the electronegativies and has direction from positively charged atom to negatively charged atom.
Oxygen has greater electronegativity than sulfur, because of that oxygen (χ=3.5) is partially negative and sulfur (χ=2.5) is partially positive.
Electronegativity (χ) is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.