Did you play with the colors?
<Color>
<InternalName>FOWUnexplored</InternalName>
<Red>30</Red>
<Green>35</Green>
<Blue>40</Blue>
</Color>
<Color>
<InternalName>FOWExposed</InternalName>
<Red>45</Red>
<Green>55</Green>
<Blue>60</Blue>
</Color>
<Color>
<InternalName>MiniMapFogColor</InternalName>
<Red>40</Red>
<Green>45</Green>
<Blue>50</Blue>
</Color>
<Color>
<InternalName>FOWBorderColor</InternalName>
<Red>50</Red>
<Green>55</Green>
<Blue>60</Blue>
</Color>
<Color>
<InternalName>FOWGridColor</InternalName>
<Red>255</Red>
<Green>0</Green>
<Blue>0</Blue>
<Alpha>0</Alpha>
</Color>
<Color>
<InternalName>FOWStarColor</InternalName>
<Red>100</Red>
<Green>110</Green>
<Blue>125</Blue>
</Color>
Each race I think has its own Fow Unexplored color that overrides the default:
<Color>
<InternalName>TerranFOWUnexplored</InternalName>
<Red>25</Red>
<Green>25</Green>
<Blue>30</Blue>
</Color>
Edit:
Scratch that the overide is commented out in UIColorDefs.xml
Also I think you want 0 transparancy (so the stars dont show through)? 1 would be 100% 0 would be 0%.
R 64
B 64
G 64
Is Dark Grey.
R 160
B 160
G 160
Is Light grey (Similar to color in your SS)