Hi,
Yes there is a way! Without selecting anything open the properties dialog box (Tools >> Properties - if you didn't already know) and click the Quick Select button at the top - it looks like a funnel filter with a bolt of lightning next to it (this is in 2004 but the older versions should look similar).
In this dialog box, you can select object using a filtering system, ie all objects on a certain layer or all circles, etc..
Select Color from the list and pick the desired colour from the Value list. Make sure the Include in selection set option is clicked. Then when OK is pressed, all the objects with the chosen colour will be highlighted.
Then simply change the selected objects' layer by selecting it from the layer list on the object properties (or Layer, in 2004) toolbox. Hey Presto! Couldn't be more simple! Well it could, the original draughtsperson could have done it all for you!!!
I hope this helps!!
Cheers,
Paul @ basepoint designz..
basepoint designz
renegade@tiscali.co.uk