You should be able to yes, although this is under the Strip Chart Traces it should also apply to graphs also...
Under:
Library,
User Interface,
Controls Graphs Strip Charts,
Graphs and Strip Charts,
Strip Chart Traces
Set Trace Attribute
Change [Trace Attribute] to [Point Style] and [Attribute Value] to one of the following:
Values:
VAL_EMPTY_SQUARE
VAL_SOLID_SQUARE
VAL_ASTERISK
VAL_DOTTED_EMPTY_SQUARE
VAL_DOTTED_SOLID_SQUARE
VAL_SOLID_DIAMOND
VAL_EMPTY_SQUARE_WITH_X
VAL_EMPTY_SQUARE_WITH_CROSS
VAL_BOLD_X
VAL_SMALL_SOLID_SQUARE
VAL_SIMPLE_DOT
VAL_EMPTY_CIRCLE
VAL_SOLID_CIRCLE
VAL_DOTTED_SOLID_CIRCLE
VAL_DOTTED_EMPTY_CIRCLE
VAL_BOLD_CROSS
VAL_CROSS
VAL_SMALL_CROSS
VAL_X
VAL_SMALL_X
VAL_DOTTED_SOLID_DIAMOND
VAL_EMPTY_DIAMOND
VAL_DOTTED_EMPTY_DIAMOND
VAL_SMALL_EMPTY_SQUARE
VAL_NO_POINT