For more than 3 conditions, you have to use a macro.
I believe this should work for you.
<font face=Tahoma><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> Worksheet_Change(<SPAN style="color:#00007F">ByVal</SPAN> Target <SPAN style="color:#00007F">As</SPAN> Range)
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">GoTo</SPAN> Finish
Application.EnableEvents = <SPAN style="color:#00007F">False</SPAN>
<SPAN style="color:#007F00">'if more than 1 cell is changed or changed cell is not A1, exit macro</SPAN>
<SPAN style="color:#00007F">If</SPAN> Target.Count > 1 <SPAN style="color:#00007F">Or</SPAN> Target.Address(0, 0) <> "A1" <SPAN style="color:#00007F">Then</SPAN> <SPAN style="color:#00007F">GoTo</SPAN> Finish
<SPAN style="color:#007F00">'otherwise, run following code to check value of A1 and _
change colors</SPAN>
<SPAN style="color:#00007F">Select</SPAN> <SPAN style="color:#00007F">Case</SPAN> Target.Value
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Is</SPAN> = "C"
Target.Interior.ColorIndex = 3 <SPAN style="color:#007F00">'red</SPAN>
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Is</SPAN> = "H"
Target.Interior.ColorIndex = 6 <SPAN style="color:#007F00">'yellow</SPAN>
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Is</SPAN> = "N"
Target.Interior.ColorIndex = 4 <SPAN style="color:#007F00">'green</SPAN>
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Is</SPAN> = "S"
Target.Interior.ColorIndex = 5 <SPAN style="color:#007F00">'blue</SPAN>
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Is</SPAN> = "L"
Target.Interior.ColorIndex = 1 <SPAN style="color:#007F00">'black</SPAN>
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Is</SPAN> = "D"
Target.Interior.ColorIndex = 15 <SPAN style="color:#007F00">'gray</SPAN>
<SPAN style="color:#00007F">Case</SPAN> <SPAN style="color:#00007F">Else</SPAN>
Target.Interior.ColorIndex = -4142 <SPAN style="color:#007F00">'no color</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Select</SPAN>
Finish: Application.EnableEvents = <SPAN style="color:#00007F">True</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN></FONT>
You have to put the code in the correct module, though. Right-click the sheet tab and select View Code. Paste this code into the window that appears. Then this code should run whenever a change is made on that sheet.
NOTE: This code will NOT run if the cells are being changed by formulas. You need a different macro for that.