Place date on the horizontal axis. Place the price per share on the vertical axis.
If you have multiple colors, show each company by a different color. Include a legend at the bottom showing the color.
If you only have one color, use a solid line, a dashed line, a dotted line etc. for different companies. Show a legend which shows which company is the solid line, which is the dash.
Go to Yahoo finance. Type in a stock in the stock search box, such as APPL (apple, inc), once the page for appl comes up, press the button for basic chart. It will draw a graph of the stock prices of apple over time. Then you can put compare with SPY in the dialog box, and it will draw both Appl and SPY. This may give you some ideas.
How i present share prices of different companies on different dates graphically
