Since, $\sim p$ and $q$ both switch also are in series
$\Rightarrow (\sim p \wedge q)$...(i)
and $p$ and $\sim q$ both switch also are in series
$\Rightarrow (p \wedge \sim q)$...(ii)
Both Eqs. (i) and (ii) are parallel switch
$\Rightarrow (\sim p \wedge q) \vee(p \wedge \sim q)$