Best tool to draw knowledge graphs

Hi guys, I'm looking for a tool where I can draw and model knowledge graphs to place in documents and reports. Something similar to Astah for UML. Do you know any tool with which I can do that?

Thanks in advance!

Arrows is the go-to tool for graph db modelling - http://www.apcjones.com/arrows/

Thank you for your answer, Terry, seems to be a really simple tool and meets the requirement. Do you know if it is possible to open a previous saved model?

I've used the Export Markup button to both copy out and in XML, seems to work in both directions.

Thanks for suggestions. I recently started using the "arrow" tool for graph data modeling, its super cool and more importantly its free. While watching a webinar recently I came across a variation of the same "arrows" utility i.e https://neo4j-arrows.appspot.com/. What I like about this is, to represent the data domains using colors (attaching the image file for reference). However somehow it did not allow me to download/use. Wondering anyone had luck using/exploring it??

Looks like the utility I mentioned above is only for internal purpose and not available in public domain.