change Marker colors on Horizantal line

mh10

hi,
in a line graph, i have one line which is horizantal to x-axis as all 4 points on that lines has same y-axis value.
This line has 4 markers on it. i want to give different colors to all these 4 points.
I tries with orthogonal values and with beforeDrawdatapoint(), but it gives same color to all four markes, as i think all four markers has same orthogonal value.

How can i give different color to these four markers on Horizantal line?


Thanks