W – Tumbler 

Barack Obama – Renegade

Hillary Rodham Clinton – Evergreen

Jimmy Carter – Deacon

George H.W. Bush – Timberwolf

Barbara Bush – Snowbank

Ronald Reagan – Rawhide

Dwight Eisenhower – Scorecard/Providence

JFK – Lancer or Dazzle

Jackie Kennedy – Lace (Hey now . . .)

LBJ – Volunteer

Ladybird – Victoria

Richard Nixon – Searchlight

Jed Bartlet – Liberty

CJ Cregg – Flamingo

Wayne Palmer – Citadel

Source and Source

And if you want to find out what your Secret Service code name would be, try this.