The System.Drawing namespace has lots of methods and classes for creating images on the fly. You could use those to draw your plot.
To get the image on a page, you'll need to either create the image and save it to the server hard disk, and then provide a normal image tag that points to that image, or you could point the image tag to another page that does the image generation and replies with the binary stream of the image. The second way removes the need to save images to disk and saves lots of permissions headaches. Also doesn't chew up space on the disk.
Work smarter, not harder