This is on a map, correct?
Make the note interior and the note border the same color as the map background.
Obviously if either the note or the background has a pattern assigned, then this might not work. So, it’s up to you to design the colors for everything on the map.
As far as the triangle shape. If you make the shape of a note the “tag” shape, you can drag the middle handle on the pointed side of the triangle toward the opposite side and that will collapse the shape into a triangle. The is not a lot of room for the Name however --but if you play around with the handles you might arrive at a pleasant arrangement.
If you have a note that is shaped and colored and bordered the way you want then make it into a prototype and those attributes can be inherited by other notes.