Depth-first search (DFS) code in python

Can you please let me know what is incorrect in below DFS code. It’s giving correct result AFAIK, but I don’t know when it will fail.

graph1 = {
    'A' : ['B','S'],
    'B' : ['A'],
    'C' : ['D','E','F','S'],
    'D' : ['C'],
    'E' : ['C','H'],
    'F' : ['C','G'],
    'G' : ['F','S'],
    'H' : ['E','G'],
    'S' : ['A','C','G']
}

visited = []

def dfs(graph,node):
    global visited
    if node not in visited:
        visited.append(node)
        for n in graph[node]:
            dfs(graph,n)

    dfs(graph1,'A')
    print(visited)

Output:

['A', 'B', 'S', 'C', 'D', 'E', 'H', 'G', 'F']