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