Is it possible to show a legend for mapping marker instead of color?

http://holoviews.org/user_guide/Style_Mapping.html

When mapping colors it automatically creates legend, but not for markers?

Conversely, when mapping a categorical value into a set of colors, we automatically get a legend (which can be disabled using the show_legend option):

categorical_points = hv.Points((np.random.rand(100), 
                                np.random.rand(100), 
                                np.random.choice(list('ABCD'), 100)), vdims='Category')

categorical_points.sort('Category').opts(
    color='Category', cmap='Category20', size=8, legend_position='left', width=500)