<｜begin▁of▁sentence｜>### Instruction:
Given a pre-existing igraph Graph instance named 'graph', how can you utilize the AbstractCairoGraphDrawer class to draw and save the graph as an SVG file using the Cairo backend?
### Response:
import igraph as ig
import cairo

# Assume 'graph' is an igraph Graph instance
# We will use the Cairo backend to draw the graph

# Initial setup
surface = cairo.SVGSurface('output.svg', 600, 400)
context = cairo.Context(surface)

# Instantiate a GraphDrawer, here CairoGraphDrawer because we are using the Cairo backend
drawer = ig.plot(graph, target=surface)

# Drawing the graph using the Cairo backend
drawer.redraw()

# Finish and write to file
surface.finish()
<|EOT|>
