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