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