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