Guild command looks correct...
Keep in mind, i dont think the command creates a guild. Make sure the guild is created, and you are using the correct ID for that guild.
If you dont already have:
If you download SQLyog or some similar program:
SQLyog
You can 100% check the guild ID in the database easily
example:
-
http://img185.imageshack.us/img185/5871/guildyq9.jpg
As for the color of the guild names... No way you can change the color. BUT
If your character is Anon. (/anon ingame) the name is purple. If hes not anon, the name is blue.