See the book by Chandler and Magnus for a detailed history of combinatorial group theory.1
A proto-form is found in the 1856 icosian calculus of William Rowan Hamilton, where he studied the icosahedral symmetry group via the edge graph of the dodecahedron.
The foundations of combinatorial group theory were laid by Walther von Dyck, student of Felix Klein, in the early 1880s, who gave the first systematic study of groups by generators and relations.2
Chandler, B.; Magnus, Wilhelm (December 1, 1982), The History of Combinatorial Group Theory: A Case Study in the History of Ideas, Studies in the History of Mathematics and Physical Sciences (1st ed.), Springer, ISBN 978-0-387-90749-9 978-0-387-90749-9 ↩
Stillwell, John (2002), Mathematics and its history, Springer, p. 374, ISBN 978-0-387-95336-6 978-0-387-95336-6 ↩