The WebOffice mobile client also supports showing legends. More details on the configuration of a legend see chapter Legend. To call the legend pick the symbol next to the corresponding map view.
On large displays the legend will be shown above the lower segment of the toolbar.

Legend above the lower toolbar - large display
On small displays the legend will be shown directly in the tab of the map views.

Legend in the map view tab - small display
Note: If the legend is wider than the available place it will get resized proportionally.