Boxplot - Two groups, each having a different number of groups

Hi,

In the following image I have plotted the average final score values for two methods: CE and STSS. There are 5 CE models and 18 STSS models. Note that STSS models has two parameters one is shown with tao, and the other has a distinct color code. How could I plot the same graph but by using a boxplot instead of a bar plot. The code to generate the aforementioned figure is attached.