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