One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,7,8,5)(9,10)(11,20)(12,17)(13,18)(14,27)(15,19)(16,23)(21,37)(22,38)(24,32)(25,34)(26,36)(28,33)(29,35)(30,39)(31,40)(9,11)(10,16)(12,21)(13,23)(14,28)(15,24)(17,31)(18,32)(19,33)(20,27)(22,26)(25,39)(29,40)(30,36)(34,37)(35,38) involution — undirected(1,3,4,8)(2,5,6,7)(9,12)(10,17)(11,21)(13,25)(14,29)(15,26)(16,30)(18,34)(19,36)(20,37)(22,24)(23,39)(27,35)(28,40)(31,33)(32,38)(9,12)(10,17)(11,22)(13,25)(14,29)(15,26)(16,31)(18,34)(19,36)(20,38)(21,24)(23,40)(27,35)(28,39)(30,33)(32,37) involution — undirected(9,13,15,14)(10,18,19,27)(11,23,24,28)(12,25,26,29)(16,32,33,20)(17,34,36,35)(21,39,22,40)(30,38,31,37)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.