To view mask paths for selected
layers in the Timeline panel, press M.
To view selected masks in the Timeline panel, press SS
(press the S key twice).
To view
mask 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.