Let's denote the number of soft cover books as \( S \) and the number of hard cover books as \( H \). According to the problem, the ratio of soft cover books to hard cover books is \( \frac{S}{H} = \frac{8}{3} \).
We know that there are 222 hard cover books, so we can set \( H = 222 \).
Using the ratio to find \( S \):
\[ \frac{S}{222} = \frac{8}{3} \]
Now, we can cross-multiply to solve for \( S \):
\[ S \cdot 3 = 8 \cdot 222 \]
Calculating the right side:
\[ S \cdot 3 = 1776 \]
Now, divide both sides by 3 to find \( S \):
\[ S = \frac{1776}{3} = 592 \]
Thus, the bookstore has 592 soft cover books.