てめえ means “you” in a very aggressive and rude way and ら is the suffix which makes it plural, so てめえら means “you all” or “you guys”.
There is another similar suffix which is たち but with てめえ, ら is more commonly used than たち as ら also implies the speaker is looking down on the people, so it’s often used with disrespectful pronouns like てめえ, おめえ, 貴様 and so on, whereas たち doesn’t have that kind of nuance.
の is the possessive particle and 血 means “blood” so てめえらの血 means “your blood”. And は is the particle which indicates the topic of the sentence.
何色 is combined with 何 meaning “what” and the suffix 色 meaning “colours” so 何色 means “what colour”. By changing the suffix, you can modify the question, for example, 何人 (なにじん) meaning “what nationality”, 何語 meaning “what language”, and 何味 meaning “what flavour”. Remember that you read it as なに, not なん. It’s read as なん when it’s attached with a counter suffix such as 何時 meaning “what time”, 何歳 meaning “how old ” and 何人 (なんにん) meaning “how many people”.
Lastly, だ in the end of the sentence which contains a question word like 何 (what), 誰(who), どこ(where) and so on, is used to demand information in male speech which often sounds strong and authoritative. For example, when a teacher finds cigarettes in a student’s bag, he would say これはなんだ？ meaning “what is this?”, or when a boss in the office is looking for his subordinate Yamada, he would say 山田はどこだ？ meaning “where is Yamada?”.