Molar Absorptivity of Copper(II) Sulfate
These are the absorbance spectra of copper sulfate in water (open markers) and heavy water (filled markers) (1):



The absorbance in water is maximum at 780 nm, as stated in the reference. From the spectrum, the molal absorption coefficient, at 780 nm, appears to be approximately 12.5 $\mathrm{(mol/55.51 mol \ of \ water)^{-1} cm^{-1}}$ with aquamolality equal to 0.5.

Since only ordinary water, i.e., $\ce{H2^16O}$, is of interest in the OP's question, the aquamolality is the same as the molality, so the solution is simply 0.5 molal. The measurements were reported to have been made at room temperature, with no specific temperature given. Hence, the solution molarity is approximately 0.5 M.

Reference


G. Jancso, "Effect of D and $^{18}O$ isotope substitution on the absorption spectra of aqueous copper sulfate solutions", Radiation Physics and Chemistry, 74 (2005) 168-171.