Patterns in all tiers were originally supposed to come from woodworkers. My tailor has never been able to make his own patterns and has always relied on the kindness of strangers... well, ok... on the kindness of my woodworker, to make them.
Then, interdependancy was done away with and the recipes became available in, (I believe), the weaving books. The first or maybe second of these should have the recipe you're looking for.
They can be purchased in the crafting instance from the same NPC you buy fuel from. Right click and examine before you buy to be sure you're not purchasing a book you don't need.
Could be worse... here, we have a single "generic" pattern for each tier but back in EQ, you needed a unique pattern for each and every item of clothing you wanted to make. And one for backpacks, and one for bags, and one for...