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