If you don't know about the color wheel here it is:

There are 3 primary colors - Red Yellow Blue
3 secondary colors (when you mix two primaries) - Green Orange Purple
and 6 tertiary colors (when you mix a primary and secondary) ex. red mixed with orange is "Red-Orange"
All together that's twelve.
Well there are also 12 separate notes in music. Some person a very long time ago decided to assign a letter name to each pitch (instead of a color - why I have no idea). The letters go from A-G and they are the white keys on a piano. The black keys are notes that are basically in between the white keys and are designated with a "#" symbol. Again, this pattern won't make sense to the non musician, but please keep reading. They are as follows:
A A# B C C# D D# E F F# G G#
This pattern repeats itself over and over as the notes become higher or lower in pitch.
12 colors and 12 notes. 12 and 12. LIGHT BULB!!! Hopefully I'm not the first person to have thought of this but here it goes...
I picked red as a visual starting point and the letter "A" note as a musical starting point. Laid out on a piano it looks like this:

Very pretty I know. The true colors are "in the middle" and as you get higher in pitch they get lighter. As you get lower, they become darker. Pretty simple. What you should basically take away from the color description is that on a piano the pitches move in a linear fashion. The next note in the pattern is EXACTLY NEXT TO THE PREVIOUS. Either above or below.
So here is where it get's interesting. There are a few different sections of instruments in the steel pan family. Each section has a different range of notes and therefore a different layout. I play a set called double seconds. Here they are:

The reason I presented a narrow section from the piano is because those are the exact notes and ranges I have on my instrument. For you musicians it is F3 to A#5. So when I apply the same exact colors to the same exact pitches on pan, it looks like this:

Not even close to a piano.
Another quick comparison. Here is a simple C major scale on piano. See how linear it is. Straight up.

Here is the exact same scale on my pans.

At this point I should note that in some ways this instrument is actually easier for me as my brain thinks about the world a great deal in terms of space and dimension. For that reason I've come to realize that I think about the music I play on pans as shapes as opposed to actual notes. I think this may be the case for many people and that is why so many other musicians may enjoy playing the instrument.
There are far more comparisons that can be made with both color and music theory but I will refrain from nerding-out on those right now. However I hope this has helped some of you at home understand this instrument a little better.