By default, ThingWorx does not provide functionality to use vector graphics in Mashups. However, it is possible to develop a client-side extension to support this format. If this is something you're interested in pursuing, I can provide you with documentation to get you started.
I believe Adam was talking about a generic Extension Development guide that can be found here: https://marketplace.thingworx.com/-/media/Marketplace/Download%20Item/Related%20Content/E/ThingWorx%20Extension%20Develo…
Other important artifacts that is necessary to create such an Extension can be found here - it's a set of libraries useful for Extension creation: https://marketplace.thingworx.com/Items/extension-sdk
Additionally, there is Eclipse Plugin that also speeds development up, that can be found here: https://marketplace.thingworx.com/Items/eclipse-plugin-for-thingworx-extensions
As far as I know, there is no special guide only for SVG extension creation or SVG handling. You need to create your own, custom Extension to display that.
Hope it helps.