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