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