Far be it from me to insert words into Jim's mouth, but I think what he might be suggesting,
@syedala , is that you're asking the wrong question...or considering a path that is more complicated than it needs to be.
If all you want is something that outlines roles and responsibilities, as well as how the functions (positions?) interact, you can more than likely accomplish this with the use of traditional tools such as job descriptions and an organizational chart.
If, however, you are looking for something more process-centric (e.g., conducting a supplier audit, purchasing/procurement process, evaluating critical suppliers, etc.), then perhaps a flow chart will work for you. At my org., we often use something like the attached, as it shows WHO is responsible for conducting WHAT and WHEN (at least within the process).