One way to interpret is the one which you have stated that the waveform is leading. The other way is the one which your calculator is not allowing you to understand, usually in some calculators this issue occurs that if the phase angle goes more than 180 degrees, they just convert it into a negative number. If you add 180+25 degrees to the current phase angle you will see what the actual phase angle is which would be 205 degrees and then you will get what you expect, that is a lagging voltage across the capacitor.
Now... why add 180+(magnitude of the number)? In my calculus class when complex numbers were being taught we used to draw the real and imaginary axis, taking the imaginary part to be negative and real part to be positive that is the vector (in the circuits case which is a phasor) lies in the third quadrant, now if something lies in the third quadrant you can be sure that the angle will be greater than 180 degrees, what the calculator does is it takes the angle from the negative x-axis rather than the positive one and since it does that and is still going counter clockwise, we get the negative sign, so we add 180 to get the angle from the positive x or real axis, which is usually from where it is measured
Speaking in terms of circuits what happens is, getting -25 degrees does not mean that the voltage has started to lead the entire input, it means that it lags it by 205 degrees, but 205 degrees is such a big lagging (usually anything above 180 degrees is) that we just say that it sort of looks like it is leading, which is actually what is done when we see something having a phase shift of greater than 180 degrees because the waveforms just give a better feel the other way around ie leading instead of lagging because the waveform of the output looks to be coming before the input one.
Real sorry for not being able to give you the graphical interpretations at the moment which would have given a clearer picture of what is above but if you plot the waveform of the circuit, you will see that the phase difference between the output and input, that is
output_angle - input_angle
will be positive if you start from the angle of the input waveform , and will be negative if you start from the angle of the output waveform of the angle