There is a lot of work left if you havent started this yet:
1. Create an SQL server with relevant information
2. Create a program that could read (and possibly write) the data in your server
3. Import the Visio Interop and start printing the graph see link below:
http://www.c-sharpcorner.com/UploadFile/mgold/VisioInDotNet12032006222024PM/VisioInDotNet.aspx[
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So what have you got ready, and what do you need help with?