Category Overlay Lines
On the Plot: General tab of the Graph Options dialog, select the Multiple lines check box and click the Multiple lines button, or in the General dialog (accessible by right-clicking on any line in a graph and selecting General Plot Options from the shortcut menu) to display the Category Overlay Lines dialog.
Pattern
Click any of the Pattern buttons to display the Line Properties dialog, in which you can change the width, color, pattern, and style of lines on the graph.
Close
Click Close to accept your changes and return to the previous dialog.