If you use SEF Service Map from  Radosław Kubera as your sitemap component you can use SQL 2 Excel Integrator for SEF Service Map 2 to show your Sections, Categories as well as Workbooks from SQL 2 Excel in your Site Map.

It is possible to show only the Sections and Categories of SQL 2 Excel, or you can also include links to the Spreadsheets.

You can control icons, descriptions and if the links points to the Spreadsheet itself, or to the Preview.

The SQL 2 Excel Integrator for SEF Service Map 2 can be downloaded here:

SQL 2 Excel 3-rd party plugins and extensions