On top of what others have said, most Brits (even a lot of remainers) are under the deep delusion that Rejoin means Rejoin on 2016 terms.
Earliest rejoin is 10 years in theory, but in reality it will probably be decades before the Brits are ready to swallow their pride and join the EU on the same terms as everyone else (no funny license plates, blue passport, no funny big ag exemptions, no more special opt-outs, and most importantly immediate euro adoption). The EU does not have any more political incentive to offer the broad exemptions the UK used to benefit from, and have publicly stated as much.
If a British party ran on a rejoin campaign and actually won, they’d fuck themselves about as hard as Cameron did because the political reality does not match the ludicrous expectations. If Brits have to turn in their Pound notes for Euro notes, the political backlash will be so enormous that it will set off seismometers in Bucharest.
It makes some sense contextually.
Purple and light purple are “NFP (left)” and “not NFP (left)”. Socialists are traditionally red.
The two blues are “LR (right)” and “not LR (right)”. Liberals are traditionally blue.
Yellow are center-right neolibs.
The independent left/right seats don’t matter much because they will vote predictably with their political side on most issues, so since this will be a coalition Parliament there is not much point in outlining individual party affiliation (anyways the NFP is already a coalition of several parties).