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