graph twoway scatter x1 y,symbol(cirlce) msize(lagre) || scatter x2 y,symbol(diamond) msize(lagre)
还有其他符号形状可以选择
circle O solid
diamond D solid
triangle T solid
square S solid
plus +
X X
smcircle o solid
smdiamond d solid
smsquare s solid
smtriangle t solid