Where can Cirrus Aircraft VisionJet Oleo Struts Material and Dimension Specifications be found?
You're after the landing gear oleo Source Control Drawings.  You need to contact Cirrus' tech support and request the drawings from their engineering organization via their support organization, who may or may not want to help you, or may charge for them if they do.

I expect they won't want to provide them because they'll suspect that it's for someone who wants to make a PMA (Parts Manufacturer Approval) copy. It's usually pretty tough to find source documentation like that for a product that is in current production.