There is no single correct way to cite standards (and most citation styles do not have a category for standards), but it is important to be consistent. Before choosing a style, check to see if your instructor has provided any guidelines or expressed any preference.
The most important thing is to include enough information that anyone reading your citation can go and find the exact document you referenced. Standards can appear in different forms (draft, active, etc.) and the same standard can be issued by different bodies. Make sure you cite the right version.