View mask paths and shapes

To view mask paths for selected layers in the Timeline panel, press M.
To view selected masks or shapes in the Timeline panel, press SS (press the S key twice).
To view mask and shape paths in the Composition panel, click the Toggle Mask And Shape Path Visibility button at the bottom of the Composition panel.
To view mask paths in the Layer panel, choose Masks from the Layer panel View menu.
To hide a mask path while showing others, lock the mask by selecting its Lock switch in the Timeline panel, and then choose Layer > Mask > Hide Locked Masks.
To isolate selected masks and hide others, choose Layer > Mask > Lock Other Masks, and then choose Layer > Mask Hide Locked Masks.