Sorry for confusion, the png was just larger than maximum size allowed, posted a new
screen on imgmur below:
http://imgur.com/sYHkIOI
.... and just found out that the vector plot is saved in home directory, and not generated
live as is the case with other plots. You can just see the icon for maxima_out.jpg under the maxima window.
P.S. Now found that the line:
terminal=jpg
is responsible for creating the image, remove this line and vector plot is generated
live in maxima like other plots
Will mark post as solved thanks for your help.