Patrick - presumably you have a function that you wish to call that will read your three sensor data values from the Arduino. An example of something similar to this may be found at http://www.mathworks.com/matlabcentral/answers/213364-receive-value-in-matlab-gui.
Now, in your GUI, you can call this function periodically so that you can update the graph and static text values. You can do this by creating a timer. See http://www.mathworks.com/matlabcentral/answers/178682-collecting-a-variable-every-two-minutes for an example of creating a timer within the GUI that periodically collects data which you can then display in the static text boxes and in the axes.
