<｜begin▁of▁sentence｜>### Instruction:
Given a graph with a circular layout, can you use the CoordinateSystem from igraph to draw the graph with custom margins and save it to a PDF file?
### Response:
from igraph.drawing import Plot
from igraph.drawing.coord import CoordinateSystem
from igraph import Graph

# Create a graph with some edges
g = Graph(edges=[(0, 1), (1, 2), (2, 3), (3, 0)])

# Set up the plot
plot = Plot(bbox=(600, 600), background='white')

# Create the coordinate system
coord_system = CoordinateSystem(plot.bbox)

# Draw the graph using the plot and the coordinate system
plot.add(g, bbox=plot.bbox, layout=g.layout('circle'), margin=50)

# Save the plot to a file
plot.save('graph_plot.pdf')
<|EOT|>
