multiaxes layouts not working

I'm trying to layout multiple graphs in the same matplotlib figure using graph_tool.draw.graph_draw on different axes.

I'm using

Python Version: Python 2.7.15 graph_tool version: 2.26 (commit b89e6b4e, Thu Nov 9 14:55:43 2017 +0000) matplotlib version: 2.2.2

Here is an example of what I would like to do:

import matplotlib.pyplot as plt
import matplotlib.patches as patches
import graph_tool.draw as gtd
import graph_tool.generation as gtg
import graph_tool.stats as gtstats
import numpy as np

plt.switch_backend('cairo')

plt.close()
f=plt.gcf()
f.set_size_inches((10,10))
rbc=(9,9)
#set up axes
a0=plt.subplot2grid(rbc,(6,0),rowspan=3,colspan=3)
a1=plt.subplot2grid(rbc,(6,3),colspan=3,rowspan=3)
a2=plt.subplot2grid(rbc,(6,6),rowspan=3,colspan=3)

b=np.random.choice([0,1],size=40)
probs=np.array([[100,10],[10,100]])


g1=gtg.generate_sbm(b=b,probs=probs)
pos1 = gtd.sfdp_layout(g1)

g2=gtg.generate_sbm(b=b,probs=probs)
pos2 = gtd.sfdp_layout(g2)

g3=gtg.generate_sbm(b=b,probs=probs)
pos3 = gtd.sfdp_layout(g3)

gtd.graph_draw(g1,inline=False,pos=pos1,
               vertex_fill_color='blue',mplfig=a0)

gtd.graph_draw(g2,inline=False,pos=pos2,
               vertex_fill_color='red',mplfig=a1)

gtd.graph_draw(g3,inline=False,pos=pos3,
               vertex_fill_color='green',mplfig=a2)

#for reference
a0.add_patch(patches.Rectangle(xy=(.1,.1),width=.9,height=.9,edgecolor='b',facecolor='none',transform=a0.transAxes))
a1.add_patch(patches.Rectangle(xy=(.1,.1),width=.9,height=.9,edgecolor='r',facecolor='none',transform=a1.transAxes))
a2.add_patch(patches.Rectangle(xy=(.1, .1), width=.9, height=.9, edgecolor='g', facecolor='none', transform=a2.transAxes))

f.savefig('test.pdf')

test.pdf