Head to Reporting > Reports > Attendance (tab) > Attendance Charts:
Then from the dropdown to select a different graphical report, select School Timeline Weekly:
You will get a graph showing whole school attendance percentages on a weekly basis. You can print this graph by clicking on the three horizontal bars to the right of the graph.
In order to understand the colour coding in this report, go to Admin > Config > Attendance Graphs
Here you can edit the Bands for each colour: