Stores that have oremium paint such as Benjamin Moore generally have a selection of coordinating historic colors and can help you select ones that are both appropriate and that you like.

If you are interested in knowing and reproducing your house's original colors, you need a specialist who can use the available technology to determine the original colors.

As pkpk23 said above, it is possible to determine the original color schemes. You might be able to get a rough guess by scraping through the paint in areas that are most likely to be original wood. Or for a more accurate methodology, there are professionals who will do scrapings, take representative samples to look at under a microscope and be able to determine which coats were primers, or the original top coat, and where original colors may have been changed by dirt or fading.

If on the other hand you are simply looking for appropriate colors, Victorian color schemes were typically warm earth tones ranging from greens to oranges and reds to yellows. See below for some typical colors:

Your house is well setup to have at least four colors, and I believe it could handle at least six different colors. I would select a color each for the siding, trim, windows, and the recessed panels in the gable end and between the first floor and second floor windows. One typical color scheme would be green for the siding, a buff or pale gold color for the trim and a darker version of the trim for the panels. The windows and storms could than be painted a dark green, or for a pop of color a cinnamon red. Windows typically were dark in color on Victorian houses.

For a more complex color scheme the second floor can be a slightly darker shade of the same hue used on the first floor. Also a sixth accent color that is in the same color range as the trim or windows could be employed to accent places like the porch ceiling, the brackets below the third floor, and the details of the front gable trim (bargeboard) that are currently getting lost.

This color scheme is a little different than the one described above, but gives you an idea of how greens, yellows, and reds were historically employed on Victorian houses:

Here is an example that uses green with brown instead of yellow, and makes greater use of red. Note that this is a pretty elaborate house with I believe a 16 color paint scheme, and there would be no expectation that your house would ever need that many