Implementation of a graph in C to SVG

Hello how are you I'm new to the mailing list and I have many doubts about
a number of programs that I am creating in C and iam having problems with
functions for graphs, and I am working with linux and gcc and good geany
After my presentation I am trying to solve a problem concerning graphs not
well as generating a SVG figure bearing the signature of the function:

char * grafica_genera_svg (struct graph * a, struct list * t, func_a_cadena
f);

The function, as its name implies, creates a document Scalable Vector
Graphics (SVG), with a graphical representation of the graph

For and tree the C implementation and SVG was with this: and generated with
the following code:

https://gist.github.com/gasparenaide/41930d45ccf521b547ce

something like this was to generate a svg document representing a tree The
function only received the tree (and a func_a_cadena type function for
convert strings of the same elements. The function returned one string
containing the XML SVG.

Now for graphs, how can i implement the C function in the svg code to
generate the graph?? Could any help me please? WOULD truly saving my life