There is no official slide archive for XSEDE presentations. However, there are pages containing links to slides and documents which may be of use. Some are listed here.
You should be able to find all logos, templates, and other official XSEDE promotional material here.
The Confluence pages for XSEDE Quarterly Staff Meetings may be a good source:
As mentioned above, there is no official slide archive for XSEDE presentations. The XSEDE Confluence site is probably the best place to put slides which you would like to make available to the public. If you choose to do so, please let us know and we will update this page.
When you have time, please respond to the New Staff Guide Feedback Survey so your views as an XSEDE staff member can be included in this guide to make it the best it can be.