To create a pivot chart proceed as below:
Click inside the pivot table that you want to present in your chart.
Choose Insert – Chart or click in the Insert Chart icon in the main toolbar.
LibreOffice Calc automatically detects the pivot table and opens the pivot chart wizard.
Select the Chart type for the data in the chart wizard.
The data range and the data series pages of the chart wizard are not enabled. They are controlled by the pivot table.
Select the Chart Elements of the pivot chart in the wizard.
Click OK to close the wizard and create the pivot chart.