"current time marker" in the graph editor? Isn't it red? If I don;t interpret you wrongly, you might want to try Window>Setting/Preferences>Colors, under Genereal Tab, look for Animation.
Hi tom, can you be more specific? I still couldn't find it 
What i mean to do is not to change the default colors of my keys now, but to add more colors. For example, I have a list of keys with special attribute ABC, and another list with special attribute PQR, and so on. Can I set such that the list of keys with special attribute ABC in my graph editor blue color, and the list of keyframes with special attribute PQR to be red, and so on. Its a visual guide to let me look at the graph editor and I can distinguish the varius groups of special keys at one glance... any ideas?
thanks guys.