Hi, Susan. Guidelines and Standards for Tactile Graphics, 2010 does not answer your question, other than giving the wise advice to be consistent in placement of the labels.
TG 6.11.1 Simple Geometric Shapes. (Two-dimensional) does say this in 6.11.1.5: "Labels should be placed outside the shape if possible and 1/8 inch (3 millimeters) away from the shape or point symbol."
Some teachers may request that labels be placed as they appear in print, to make it obvious to non-braille-reading assistants what they are looking at.
However, I would suggest putting the labels in the proper cell for a displayed expression, aligned with the top part of the drawing which then is placed to the right of the label.
The five shapes should be arranged vertically on the braille page, not horizontally as in print.