The Jacks head to the Mestalla on Thursday, August 19 to take on Los Che in their opening Group A meeting and Dyer is looking forward to the Welsh club testing themselves against the best.
"Everyone knows who Valencia are," he told the club's official website.
"It's going to be great for us to play a team like them. Obviously Pablo (Hernandez) came from there, and he knows all about the team.
"It's going to be a really tough test for us; they've had some quality players, and they are a massive team - especially in Europe."
Swansea will also meet Swiss side St Gallen and Russia's Kuban Krasnodar in the group stage of Europe's second tier club competition.