EDIT: I went back to the puzzle long after I'd forgotten my answer key to see if I could solve it. Well, I did. Took about 20 minutes. Here's how I did it.
There are four vertical positions in both the color set and the moon set - first, second, third and fourth position (from the top).
Look at the colors long enough and you'll notice that each color is represented in each position only 3 times. The first position (in total) has 3 red, 3 black, 3 yellow, and 3 blue. This repeats for all the positions - the second position has 3 red, 3 black, 3 yellow, and 3 blue; the third position has 3 red, 3 black, 3 yellow, and 3 blue; and the fourth position has 3 red, 3 black, 3 yellow, and 3 blue.
Knowing this, looking at the moons should make it immediately apparent which is the odd one out (Norrus) - in first position there are FOUR instances of the "left" moon. Going along to different positions will show you that moon placard IV is the odd one out, whose every symbol breaks the "three appearances per position" rule. So we know we need to translate the moon symbols on the "IV" plate to find the order in which Norrus's colors should be arranged (Left, up, down, right).
With me so far? Ok, here's how I went about cracking which colors mean what.
I started looking at patterns in groups of two. Though each color appears exactly three times in each position, pairs of colors do not. Looking at the first pairs (positions 1 and 2), we see three color pairings appear twice: black-red, yellow-black, and red-yellow. Moon pairings at the same position (ignoring placard IV because we know it's Norrus') show us another three pairings appearing twice: up-left, right-up, and left-right.
From this we can infer three scenarios:
1) black = up, which means yellow = right, red = left, and blue must = down
2) yellow = up, which means black = left, red = right, and blue must = down
3) red = up, which means yellow = left, black = right, and blue must = down
Either way, we know blue MUST be down, as both "blue" and "down" don't appear in any of the pairings of the first two positions.
From here you troubleshoot by direct comparison using the assumption of the scenario to see if it fits. Translate the moon plates into their colors according to the assumption, and see if the color combinations are all present and accounted for.
-Using assumption #1 (black = up), we find that placard VII doesn't fit the scheme (Red-Blue-Black-Yellow doesn't exist).
-Using assumption #2 (yellow = up), we find that placard II doesn't fit the scheme (Blue-Red-Yellow-Black doesn't exist)
- In this case, the correct assumption is assumption #3 (red = up), so Norrus's color combination (going by moon placard IV) is going to be Yellow-Red-Blue-Black.
This may be even easier if you look at pairings on another set of positions, but I went with the first two slots for convenience sake.
I suppose insight comes when it's realized that there are only three instances of each color in each position. Maybe I should make that an obvious clue somehow... though I expect that a table full of actual, intelligent "nerds" would be able to solve this regardless. I guess that's the problem inherent of puzzles in adventures: there's a wide breadth of different intelligence ranges, and you have to appeal to as many of them as you can.