Hello Yuki,
The stencils for the X620 and X870 were posted to our Extranet site, but haven't been posted to the link Steven listed above. I'll ask the web-team to update it.
They can be found in the partner resources tab on each of the product's pages on Extranet.
https://extranet.extremenetworks.com/downloads/Pages/SummitX870.aspx
https://extranet.extremenetworks.com/downloads/Pages/SummitX620.aspx
If there are stencils for the VIM, I haven't seen them.
If you don't have an Extranet account, let me know and I'll get them to you another way. Once the main Visio page is updated, this won't be a problem.