In the book Farsight by Phill Kelly, Farsight's answer in response to Brightsword's question regarding why he had painted his Crisis battlesuit deep red was:
You asked me why I changed my battlesuit colours. It is to honour the Arkunashan dead. Their blood is on my hands, and I will not forget it.
This is a compelling reason for a human who is seeking to avenge his fallen comrades. But the thing is, Arkunasha is a Tau Empire colony and Tau blood is blue or cyan. Shouldn't he have painted his suit blue instead?
Why did Farsight choose a red paint scheme to honour the Arkunashan dead? Do any of the Warhammer 40k supplements or general lore explain this discrepancy, or is this just an honest mistake? Note that GW depicts Commander Farsight in a red Crisis Suit.
After ShadowKras' answer, there is no doubt regarding Tau blood: it is definitively blue (or cyan to be more precise). This leaves us with the original question: why is Farsight's suit red?
As for now, I can only think of one possibility myself. Given that Farsight is a WH40K character that has been there long before the book Farsight, Phill Kelly tried to justify the suit's color by relating the to spilled blood, but made a honest mistake by not remembering that Tau blood is blue.
Can anyone confirm/deny this? Is there a different reason why the suit is red?