This sounds like a two part problem.
Part 1 is figuring out how to get the raw data from the server. Without knowing what sort of server this is, there isnt much to say. If the server does not yet exist, and depending on the frequency and size of the data being sent, you might look at making http requests from the Android client and retrieving either XML or JSON formatted data.
Part 2 is creating and updating the graphical component(s) on the Android. Yes you could do this from scratch using the Android 2D graphics library, but why reinvent the wheel? Take a look at AndroidPlot - http://androidplot.com. AndroidPlot supports dynamic datasources so as soon as you've got your client code in place, you can easily hook that up to an AndroidPlot generated plot widget and redraw it every time you receive an update from the server.