Hi Jyoti raina,
I think one way to get the graph of your wish is that :
first get the results in terms of Q-factor and BER for each receiver with respect to length of fiber.
Put all the values of q-factor and ber for corresponding fiber length in Excel.
Now you can plot the graph for Q-factor and BER separately with respect to length of fiber for all 4 receivers in same graph window and now compare the results of BER and Q-factor for each Receiver.
Here i am uploading image in which i compare Q-factor for NRZ and RZ modulation formats wrt length of fiber.
In same image we can plot 3 or 4 results as per our convenience.
Hope this will help you.