color_select = bokeh.models.Select(title='Select colors', value='colors1',
    options=['colors1', 'colors2'], callback=cb_cselect)
layout = bokeh.layouts.gridplot([[p], [color_select]])
bokeh.io.output_file('output.html')
bokeh.io.show(layout)
Bokeh, how to change column used for glyph colors with CustomJS callbacks?