Q. What is a Swatch?
A. It is the icon you see next to the appearance text when you are creating your Faction/Factions with the in game editor.
There are mods out there that add appearences but I have yet to see people actualy make the swatches for them. This is a brief guide on how to make them.
What you need
Aidens Gradient Maps.
A program like Paint.net.
Download this zip. It contains a Template.
What you need to do
I am going to asume that you are using Paint.net. The instructions should be universaly viable. Now in my template I have included and extra color this is for Secondary Lights, the default swatches do not show this.
Open both of Aidens Gradients in Paint.net.
Open my template in Paint.net.
Select the fill tool. Turn Antialiasing OFF (The squiggly line with 3 dots on it, on the topbar), Change Clipping mode to Pixelated(The little square with 4 dots on it, on the topbar).
Open your Appearance.xml in the text editor of you choice.
When you create or created your appearnace you setup a bunch of colors:-
<GC3Appearance>
<InternalName>ST_Vulcan_Appearance</InternalName>
<DisplayName>Ship_Color_Vulcan</DisplayName>
<DisplayIcon>Vulcan_Appearance_Icon.png</DisplayIcon>
<!-- Ship Colours Row 1 is Primary, Row 2 is Secdondary-->
<DiffuseGradientRow1>170</DiffuseGradientRow1>
<DiffuseGradientRow2>174</DiffuseGradientRow2>
<!-- Main Lights -->
<LightGradientRow1>102</LightGradientRow1>
<!-- Cockpit & Secondary lights -->
<LightGradientRow2>102</LightGradientRow2>
<!--Engine, not sure what this does, I think it is the engine stream since the actual engine color is set in RGB Below -->
<LightGradientRow3>58</LightGradientRow3>
<!-- Materials -->
<SurfaceScale1>10.0</SurfaceScale1>
<SurfaceWeight1>1.0</SurfaceWeight1>
<SurfaceScale2>20.0</SurfaceScale2>
<SurfaceWeight2>1.0</SurfaceWeight2>
<!-- Engine Colour in RGB -->
<EngineColor>
<Red>0</Red>
<Green>102</Green>
<Blue>204</Blue>
<Alpha>255</Alpha>
</EngineColor>
</GC3Appearance>
This picture shows what each Box/Line in my template does.

Now select the Picker tool. Goto the GradientMap.png. Navigate to the row you chose for you main color, I picked 170 so I left click this with the picker tool to select this color as primary. Then Navigate to your second color, I chose 174 so I right click this with the picker tool to select this color as secondary.
Goto the Swatch Template, select the fill tool, left click on the first box then right click on the second box. The two colors we picked will be filled in these boxes.
Deselect the fill tool by selecting Rectangle Select tool. Select the Picker tool again.
Goto the GradientLightsMap.png. Use the picker tool to select the colors you set in the LightGradientRow's, I went with 102 for both.
Back to the Swatch template. Select the Fill tool and color in the next 2 lines with your colors. Left click first line, right click second line.
Now the Engine color is set in RGB. I use this site to enter in the RGB vales and get an idea of the color. I then use the Picker tool on the GradientLightsMap.png to get the color as close as I can to this RGB color. An fill this in on the last line in the template.
Goto File - SaveAs and save your new swatch!
Hope this help some. I am not very good at writing up guides!