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