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