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