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