Sure, both sides were led by members of the senatorial class. Both ex-magistrates (the same thing as a member of the senate, provided that it was a senatorial magistracy--both sides fielded plenty of non-senatorial magistrates) and serving magistrates and promagistrates served on both sides. After all, armies were raised by provincial promagistrates, as consular and praetorian armies were only a minor source of military forces by the time of the civil war. Most notably Cato (an ex-magistrate) and Metellus Scipio (proconsul for Syria at the time) served as commanders in Pompey's army--Cato commanded the city during the siege of Dyrrachium and Scipio commanded the center of Pompey's infantry line at Pharsalus and would command the Republican army at Thapsus. Caesar's own colleague during his consulship in 59, Bibulus, who in 49 had just finished his proconsulship in Syria, commanded Pompey's Adriatic fleet, despite being a political opponent of Pompey's, and failed to prevent Caesar from crossing over with the bulk of his army. But the division was not along senatorial lines at all. Caesar's staff contained plenty of notable senators and magistrates--Domitius Calvinus (consul of 53) led Caesar's initial expedition into Greece alongside Lucius Cassius, brother of Caesar's assassin, who sided with Pompey during his tribunate in 49. Curio, quaestor of 54, served to protect Caesar's rear while he was at Pharsalus, seizing Sicily from Cato and making an expedition to Africa, where he was killed. On the other side of the coin, Labienus, an equestrian who served as tribune of the plebs of 63 and Caesar's most important legate in Gaul but who never held a senatorial office and was thus not of the senatorial class, had defected to Pompey early on and commanded Pompey's cavalry admirably at Pharsalus, only to be outwitted by Caesar. Curio was initially an ally of Clodius' and an opponent of Caesar's, and shortly before the civil war attempted to pass legislation disarming both Pompey and Caesar, instead of just Caesar (he lost by one vote). The Cassii fought on different sides, despite being of the same class (although Gaius had entered into the senatorial ranks after his quaestorship of course, and Lucius had not yet held a senatorial magistracy). The senate was not some homogeneous block of like-minded people--indeed, one of the many reasons for political instability in the period was that the individual members of the senatorial class couldn't get along with each other and wouldn't agree on anything. Individuals decided for themselves whose side they were on, and just as many notable politicians sided with Caesar as with Pompey (then of course there's the division within Pompey's camp--Cato's faction didn't like Pompey and Pompey didn't like them, but he was the lesser of two evils and served as the only guy who could take on Caesar, so it was worth it). That's just a very cursory list of whoever happened to stand out at me--there are many, many more, and I'm largely not including people of senatorial families who had not yet attained a senatorial office (like Lucius Cassius, whom I did mention) or holders of non-senatorial magistracies.