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