OpenOffice: Templates for Diagrams

I have a great number of diagrams in an Open Office Writer document (text processing program). All of those graphics are looking differently and I would like to bring them to an equal status and look.

I know, it is possible to use central style sheets for text. With this, you are able to modify, for example, the template for headings or text blocks centrally and the changes or modifications are then applied to all such elements all over the document. For instance, when changing the font in one of those stylesheets, automatically all occurrences within the whole document are changed.

Now I need the same for diagrams. That is, I need a template or style sheet in which I can define for all of diagrams all over the document a consistent font (size, style, typeface, bold, italic etc.), uniform axis, unified spacing (margins, borders etc.) or consistent colors and lines (for example for the bars). Those settings should then automatically change all diagrams of my document. Is that possible?

Unfortunately, I have nothing but found for that. It would save me a lot of work, because otherwise I would have to open each diagram individually in order to edit all of the style and this is really very time consuming.