You can specify {\tt linewidth, linecolor, fillstyle, fillcolor} on most PSTricks objects. For example:

\begin{center}
\begin{pspicture}(-2,-2)(2,2)
\psline[linecolor=green]{->}(0,0)(1.2,1.2)
\psline[linecolor=red]{->}(0,0)(-1.2,-1.2)
\psline[linecolor=purple]{->}(0,0)(1.2,-1.2)
\psline[linecolor=lightblue]{->}(0,0)(-1.2,1.2)
\end{pspicture}
\end{center}

Which can be created with the following source:

\begin{verbatim}
\begin{pspicture}(-2,-2)(2,2)
\psline[linecolor=green]{->}(0,0)(1.2,1.2)
\psline[linecolor=red]{->}(0,0)(-1.2,-1.2)
\psline[linecolor=purple]{->}(0,0)(1.2,-1.2)
\psline[linecolor=lightblue]{->}(0,0)(-1.2,1.2)
\end{pspicture}
\end{verbatim}

Fill modes can be useful to show things like integration and area:

\begin{interactive}
\begin{center}
\begin{pspicture}(-4,-3)(4,3)
\psplot[algebraic,linewidth=2pt,fillstyle=solid, fillcolor=lightblue]{-1.5}{1.5}{sin(x)}
\psplot[algebraic,linewidth=2pt]{-4}{4}{sin(x)}
\psline{->}(-4,0)(4,0)    
\end{pspicture}
\end{center}
\end{interactive}
\begin{print}
\begin{center}
\begin{pspicture}(-4,-3)(4,3)
\psplot[algebraic,linewidth=2pt,fillstyle=solid, fillcolor=lightblue]{-3.14}{3.14}{sin(x)}
\psplot[algebraic,linewidth=2pt]{-4}{4}{sin(x)}
\psline{->}(-4,0)(4,0)    
\end{pspicture}
\end{center}
\end{print}

Which can be created with the following source:

\begin{verbatim}
\begin{pspicture}(-4,-3)(4,3)
\psplot[algebraic,linewidth=2pt,fillstyle=solid, fillcolor=lightblue]{-1.5}{1.5}{sin(x)}
\psplot[algebraic,linewidth=2pt]{-4}{4}{sin(x)}
\psline{->}(-4,0)(4,0)    
\end{pspicture}
\end{verbatim}

basic graphics parameters