Question

plot a speed time graph when the initial velocity is not zero and the body is undergoing increase in speed uniformly with time

Answer 1

Speed v increasing uniformly =>  acceleration a  is constant
u = inital velocity not 0.
  v = u + a t
        it is like y = m x +  c     where u is the intercept on y axis,     a is the slope of the curve.
         Here a is positive and so the line is sloping upwards.

Answer 2

This is the graph for that situation.