One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(6,8)(12,19)(16,21)(17,23)(22,24)(25,26,31,28)(27,33,29,32)(30,36,38,34)(35,39,37,40)(1,2,4,5)(3,6,7,8)(9,10)(11,15)(12,16)(13,14)(17,22)(18,20)(19,21)(23,24)(25,27,31,29)(26,32,28,33)(30,35,38,37)(34,39,36,40)(10,14)(15,20)(16,21)(22,24)(26,28)(27,29)(34,36)(35,37) involution — undirected(9,11,13,18)(10,15,14,20)(12,17,19,23)(16,22,21,24)(25,28,31,26)(27,33,29,32)(30,36,38,34)(35,40,37,39)(9,10)(11,15)(12,16)(13,14)(17,22)(18,20)(19,21)(23,24)(25,29,31,27)(26,33,28,32)(30,37,38,35)(34,40,36,39)(1,3,4,7)(2,6,5,8)(9,12)(10,16)(11,17)(13,19)(14,21)(15,22)(18,23)(20,24)(25,30,31,38)(26,34,28,36)(27,35,29,37)(32,39,33,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.