Code:
set scheme s2mono
* Example generated by -dataex-. To install: ssc install dataex
clear
input double(cseA id group)
3   1 1
4   2 2
4   3 1
4   4 1
4   5 1
4   6 2
4   7 2
4   8 1
4   9 1
3  10 1
4  11 1
4  12 2
3  13 1
4  14 1
4  15 2
4  16 1
3  17 1
4  18 2
5  19 2
3  20 1
4  21 2
3  22 2
3  23 1
3  24 2
3  25 1
4  26 1
3  27 1
5  28 2
4  29 2
4  30 1
3  31 1
5  32 2
4  33 1
3  34 1
4  35 1
4  36 1
3  37 1
5  38 2
5  39 2
3  40 1
4  41 2
4  42 2
4  43 2
3  44 1
3  45 1
4  46 1
4  47 1
4  48 2
4  49 1
4  50 1
3  51 1
3  52 2
4  53 1
4  54 1
3  55 1
4  56 2
4  57 1
4  58 2
4  59 2
4  60 1
4  61 2
5  62 2
4  63 1
4  64 2
4  65 2
4  66 1
3  67 1
3  68 1
5  69 2
4  70 2
3  71 1
4  72 2
3  73 1
3  74 1
4  75 1
3  76 1
3  77 1
4  78 2
4  79 1
3  80 1
3  81 1
4  82 2
4  83 1
4  84 2
2  85 1
4  86 1
4  87 2
4  88 2
4  89 2
3  90 2
3  91 1
3  92 1
3  93 2
3  94 1
4  95 2
4  96 1
3  97 1
4  98 1
4  99 2
4 100 1
end
graph bar (count) id,    over(group,relabel(1 "group1" 2 "group2") label(angle(45)) gap(0) )  over(cseA) blabel(bar) ytitle("")
how to use color to differentiate group 1 and group 2?