As President Reagan's official representative to the Paris Air Show this month, Sen. Strom Thurmond (R-S.C.) was entitled to take along all the guests he wanted -- 57 of them, as it turned out.

The group, which included more than 40 South Carolina officials and relatives, friends and neighbors of Thurmond and his wife, Nancy, along with a half-dozen Thurmond staff members, flew to Paris at government expense on a military version of the Boeing 707, leaving June 10 and returning Tuesday. The estimated cost to the government was $140,000.

The government did not pay expenses of the air-show guests who were not federal employes while they were in France, according to Thurmond aides.

According to a list reported by Ken Burger of the News and Courier of Charleston, S.C., the entourage included a son, daughter, sister and niece of Thurmond, a former aide to the senator, Nancy Thurmond's parents and a neighbor of the Thurmonds. It also included two Washington businessmen, Dominique D'Ermo, owner of Dominique's restaurant, and Marshall Coyne, owner of the Madison Hotel.

South Carolina officials included Gov. Carroll A. Campbell (R) and his wife, a university president, several state legislators and economic development officials. Burger quoted Thurmond as saying he invited the state officials to help encourage foreign companies to locate in South Carolina "without the state having to shoulder the total costs of a trip to Paris."