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