If you look over at the recipe for raspberry meringues you will notice that it calls for raspberry extract and red gel food colouring. Those two things can be substituted for pretty much any flavor and colour. You could have purple orange meringues is you wanted to.
A little tip is that on the egg whites for you all. If you have them at room temperature before you start mixing them is that it makes it easier get the recipe right.
If you do not want your meringues to have stripes you can paint the entire inside of the bag with the gel food colour. However, only the outside of the meringue will be that colour. If you want it coloured inside and outside, mix the food colour in with the egg whites.
You do not have to use a pastry bag if you do not have one. You can use a Ziploc bag and cut one of the corners off. It works pretty much the same way. You also do not have to worry about how to get the bag closed.