Many unnamed and named characters in the Coruscant Senate Tower and elsewhere across the galaxy wear this style of senatorial robes. The outfit features tailored burgundy pants and a drab green jacket under a textured burgundy open robe, decorated with mustard yellow and drab green accents. Some jackets end at the waist, under the belt, while others extend to cover the crotch. Some senators wear a diagonal mustard-yellow sash over their chest. Some wear elaborate, boxy hats. Some robes feature an additional rounded cap sleeve on top of the robe’s normal sleeves. Some senators also wear a bulky striped scarf around their necks.
This outfit is worn by numerous characters, including Senator Evran, Minister Imogh, Senator Oranda, Senator Barc, Senator Starsnow, Senator Doleran, and Senatir Erdstale.
Jedipedia has numerous 3D turn-arounds of NPCs in this outfit under the search terms “Senator” and “Diplomat.” You can also search by specific characters’ names.