Go to your pack default folder with all your ELS files and double click on the car you want to change the lights on and then you can see the colours listed for example:
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!-<- EXTRAS OVERRIDE AND ENV LIGHTING-->
<EOVERRIDE>
<Extra01 IsElsControlled="true" AllowEnvLight="true" Color="red" OffsetX="-0.70" OffsetY="-0.20" OffsetZ="0.50" />
<Extra02 IsElsControlled="true" AllowEnvLight="true" Color="blue" OffsetX="-0.25" OffsetY="-0.20" OffsetZ="0.50" />
<Extra03 IsElsControlled="true" AllowEnvLight="true" Color="blue" OffsetX="0.25" OffsetY="-0.20" OffsetZ="0.50" />
<Extra04 IsElsControlled="true" AllowEnvLight="true" Color="red" OffsetX="0.70" OffsetY="-0.20" OffsetZ="0.50" />
<Extra05 IsElsControlled="true" AllowEnvLight="true" Color="red" OffsetX="-0.70" OffsetY="-0.20" OffsetZ="0.50" />
<Extra06 IsElsControlled="true" AllowEnvLight="true" Color="blue" OffsetX="0.70" OffsetY="-0.20" OffsetZ="0.50" />
<Extra07 IsElsControlled="true" AllowEnvLight="true" Color="blue" OffsetX="-0.40" OffsetY="-0.80" OffsetZ="0.40" />
<Extra08 IsElsControlled="true" AllowEnvLight="true" Color="blue" OffsetX="0.00" OffsetY="-0.80" OffsetZ="0.40" />
<Extra09 IsElsControlled="true" AllowEnvLight="true" Color="red" OffsetX="0.40" OffsetY="-0.80" OffsetZ="0.40" />
<Extra10 IsElsControlled="true" />
<Extra11 IsElsControlled="true" />
<Extra12 IsElsControlled="true" />
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I am not sure if this is right but hope it is for your sake.