If there is an increase in income tax rates, people will save less money at every given level of income. This is because they will have to give up more of that money in taxes and will not be able to save it.
However, if you are using "saving schedule" in the same way I would, this will not cause a change in that schedule. If the x-axis of your graph is disposable income, then the schedule should not change.
All that an increase in income tax will do is to lower the amount of disposable income. It will not affect the marginal propensity to save. So all that will happen is a move along the line, not a shift of the line.