You have to pick a notation, which allows to describe the orientation of each pentomino piece (its rotation and knowing whether it is a mirror image of its canonical image or not) and also its position relative to the other pentomino pieces (or relative to the coordinates of the square grid). Each pentomino piece can have a unique name derived from the Latin letter, which is similar to it (see image).
One suggestion is to pick one "local coordinate origin" in each piece of Pentomino (it is shown by small red circles in the above image), and to define where in your configuration each piece has been translated (e.g. 4 squares to the right and 6 squares to the bottom from the upper left corner of the grid) and also its rotation and possible mirror image properties. For example, consider the pentomino configuration show in the image below:
Most likely each of your pentomino pieces will have a (different) default color, but it will allow to be overriden by explicit "klucis:hasColor" property. So the colors can be omitted from the RDF configuration most of the time. The suggested RDF configuration for this image is here:
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix klucis: <http://www.webkursi.lv/schema/20061008/klucis#> . @prefix pentomino: <http://www.webkursi.lv/schema/20070223/pentomino#> . @prefix : <http://example.com/bildes#> . :solution6x10 a klucis:TopComponent ; klucis:hasImageName "solution6x10" ; klucis:hasContent [ a rdf:Seq ; a pentomino:Configuration ; rdf:_1 [ a pentomino:F ; pentomino:gridX 6 ; pentomino:gridY 3 ; klucis:rotate 270 ] ; rdf:_2 [ a pentomino:I ; pentomino:gridX 0 ; pentomino:gridY 0 ] ; rdf:_3 [ a pentomino:L ; pentomino:gridX 5 ; pentomino:gridY 1 ; # apply mirror image pentomino:flip "true" ; pentomino:rotate 90 ] ; ... ] .
In this case we assume that translation to (gridX,gridY) is performed first, mirror image (if "flip = true") is performed second and rotation - the last. (For a more comprehensive vocabulary of transformations, a definite sequence would be needed. Notice that we can define properties like "pentomino:flip", when we need it and supply them with custom semantics. Afterwards we can care about alligning it with mirror image operations defined for other purposes, if KLUCIS ever needs them.)